Finally, I am getting everything right on how to make the Japanese sponge cake after many attempts.

The cake is bouncy like a sponge, with the soft and delicate texture resemble cotton when you tear it apart.

I also add the cake batter to the dough of the chocolate Japanese milk bread. Here is the result- my delectable bread-cake that I missed so much after the nearby bakery decided to stop producing it.

Note: This post may contain affiliate links. Please read my privacy policy for more info. I may receive commissions for purchases made through links in this post.

How to make Japanese sponge cake in twenty minutes

This article is all about how to make the Japanese sponge cake. Please refer to this article to find out how to make the Japanese milk buns that are incredibly soft.

The process of making the Japanese cotton sponge cake is similar to most of the sponge cake recipes. Nevertheless, there are some fine details which I will explain in detail in the following sections.

1. Measure the flour and butter correctly

The importance of sieving the flour

Measure 100g of plain flour and sieve at least once. What I mean by plain flour is any wheat flour that is label as cake flour or all-purpose flour. The percentage of gluten in these type of flours is relatively low, about eight to ten percent, which is ideal for making sponge cakes.

I sieve the flour not because it is dirty. The flour that I get locally are very clean, but I want to ensure that it is free from any lumps and large particles. The fineness of the flour is critical to get the cottony texture. If you happen to get any superfine cake flour, go for it. It will significantly improve the texture of the cake. Since I have not been able to purchase it this time, I have to sieve the flour to make sure the cake will turn out well.

Use melted butter to mix with the flour

Place 75g of unsalted butter in a pan/pot over low heat until it melts. You can melt the butter in the microwave oven by using low heat for a minute. Keep an eye to the butter and do not brown it as it will alter the flavor and smell of the butter.

You may want to substitute the melted butter with corn oil. However, a sponge cake made with good quality butter has a better flavor.

Add the flour to the melted butter after it is cooled. We do not want to add the flour to the hot butter to avoid the flour being cooked at this time. We are not here to make choux pastry!

Do not worry if the flour and the butter forms a sticky mass at this point of time. It will turn into a smooth batter after adding milk and the egg yolks subsequently.

Note: This is not a gluten-free formula. I have not tried to make a sponge cake with any gluten-free recipe so far.

2. Add the milk

Add 60ml (4 tablespoons) of milk to the flour-butter mixture. You may pour all the milk into the mixture or add in batches. It will not make any difference to the result.

The milk will dilute the flour-butter mixture to form a thick paste.

3. Separate the egg yokes from the egg whites carefully

We need to add the egg yolks to the above flour-butter-milk paste to form the batter.

So far the process is relatively straight forward. There is quite easy and does not involve much technique. However, please pay attention when you separate the egg yolks from the white. It can be the make or break step for this recipe.

Do not even let a trace of egg yolks contaminate the egg whites. We need pure egg whites to prepare meringue, and it has to be free from oil to be successful. Egg yolks are oily, and that is why it has to be very careful not to break the yolks.

Here are my recommended steps:

  • Use a clean stainless steel bowl to keep the egg whites. Wipe the bowl with paper towels to make sure that it is free of oil. The bowl must be large enough as we will use it to beat up the egg whites to form the meringue.
  • Use the egg yolk separator to remove the egg white from the yolk. I always crack the egg in a separate bowl to make sure any broken eggs will not contaminate the bulk of the whites.
  • It is not possible to separate all the whites from the yolks. However, there should not be even a trace of yolk in the white as it will hinder the expansion while making the meringue.

4. Making the batter

Lightly beat the egg yolks and add to the flour-butter-milk mixture.  Again I have tried to add the egg yolks in batches to the mixture, but it makes no difference compare to pouring all the yolks at one go.

The egg yolks will dilute the paste further into a batter. It is at this time that you need to mix it thoroughly. I mean to mix it, not to beat it as beating will create bubbles that are not a welcome inclusion to the cotton-like texture.

Mix it in one direction until it is free from any visible lumps. The final batter should have a very smooth texture.

Once you have done that, you have won half of the battle. Let’s move on to prepare the meringue.

5. Beat the egg whites until it forms stiff peaks

The egg white should be at room temperature while making the meringue. Remove the eggs from the refrigerator and wait for it to return to the room temperature before cracking them.

Beat the egg whites with a hand-held mixer at low speed. If the room temperature is too low during winter, place the bowl of egg whites on a hot water bath. Warm egg whites can trap more air in its structure and expand its volume rapidly during the beating process.

  • Add 80g of castor sugar or fine sugar into the egg white after fifteen seconds of beating.
  • Continue beating the egg whites until the volume triple. The egg white will change gradually from transparent to pure white, and become thicker.
  • Eventually, the egg whites become so thick that when you switch off the electric beater and turn it upside down, the egg white that sticks onto the beater blade will become so stiff that it will firmly stand without drooping. Beat the egg whites until it can form a stiff peak.

Nevertheless, some bakers prefer to beat the egg whites to form a soft peak, which means that the peak will droop a little when you overturn the beater blade.

How to maintain the best volume for the meringue

If the meringue forms only until the stage of the soft peak, it will lose volume rather quickly while you start to fold since it is less stable. In contrary, meringue that forms stiff peak stage is firmer and need more folding until it can incorporate uniformly with the batter. The longer you fold, the batter will deflate more.

My preference is first to beat it until it forms a soft peak, then beat further by stopping every twenty seconds to check if it achieves the stage of stiff peak. I do not want to overbeat it because the meringue is hard to combine with the batter once it becomes too stiff.

I will dilute the batter with a quarter of the meringue so that it is easier to mix, then add the diluted batter back to the bulk of the meringue. Fold the meringue into the batter slowly until it is almost homogenous.

The batter will deflate beyond the optimum level if you fold the meringue until the batter is homogenous.

Then I will pour the cake mix into the cake pan. The pouring action will finish up the last bit of mixing which will eventually produce a homogenous cake mix in the pan.

Japanese sponge cake is bouncy like a piece of sponge, with the soft and delicate texture resemble cotton when you tear it open. This articles will show you every detail of how to make Japanese cotton sponge cake. (with video).

6. Line the cake pan with baking paper

Line the cake pan with a large piece of baking paper enough to cover the sides of the square cake pan. Brush the paper with some melted butter.

Since I am using a cake pan with a detachable base, I have to wrap the exterior of the pan with aluminum foil to avoid the water from the water bath from seeping into the pan.

After pouring the cake mix into the pan, you will notice there will be some bubbles on the surface. These bubbles will create little craters on the surface if you do not get rid of them. You can do this by:

  • Gently tap the cake pan a few times to break the large bubbles.
  • Use a bamboo skewer or toothpick to break the smaller bubbles.

7. Baking at the right temperature

Place the cake in the hot water bath. Once the oven is heated, bake at 150°C/300°F for sixty minutes.

But it may not be right sometimes!

The recommended temperature and baking time is one of the most unreliable measurements in any recipes for cakes. Most of the ovens do not have a very accurate temperature indicator. The heat distribution and the size of the oven is another factor that affects the final result.

My suggestion is to take a quick look at the cake after baking for forty minutes. If the cake has already expanded, then it should be fine. Otherwise, increase the temperature by 10°C to make sure the air trapped in the batter expands and push up the cake.

When the cake is nearly done, you can open the oven door more often without worrying the sudden drop of temperature will cause the cake to deflate. Check the color of the cake. The actual baking time will depend on the color of the cake. You need to check. It is not possible to set the temperature precisely each time unless the oven has a digital control panel.

8. Do not cut the cake immediately after baking

Remove the cake from the oven and water bath and let it cools on the table for fifteen minutes. The cake will shrink a little and detached from the sides of the pan.

Overturn it onto a wire rack and remove the paper. Then, place a cake board on it and revert the cake again. Now you have Japanese sponge cake ready to cut and serve.

Additional information – May 2020

I have just revisited this recipe as some of the readers were unable to produce the same result as mine while following the recipe diligently. There are two commonly happened problems that I want to address.
– The cake is undercooked at the bottom
– The cake is dense

1. Why is the sponge cake undercooked at the bottom? 
The cake is baked in a water bath. The purpose of the water bath is to provide a slow and even heat, protecting the delicate sponge texture. The cake will rise slowly and evenly with no rapid expansion, and therefore achieve a smooth and cottony texture. 

However, the water at the lower part of the cake brings down the temperature, causing the upper part to expand faster than the lower part, resulting in the bottom becomes denser than the top.

To solve this problem, I have made two adjustments:
– First, increase the temperature to 160 °C/320°F.
– Put the cake on the lowest rack of the oven. The bottom of the cake will heat up efficiently now and rise at the same speed as the top, and will not cause the formation of a dense layer. 

The water bath will still function to ensure sufficient moisture in the oven, forming a flat top surface without crack, and moist texture. 

The lowest rack of my oven is just one inch above the bottom heating element. You may need even higher than 160°C if it is further away from the heating element. You have to forgo the water bath if it still doesn’t work. There are no two ovens that behave the same. The cake will become dryer without a water bath, though.

The most common reason when the sponge cake is still uncooked after baking one hour is due to low temperature. The distance between the baking rack and the heating element makes all the difference. You know your oven best!

2. Why is my sponge cake denser than what is shown in this post? 
In my opinion, the main reason is overmixing while folding in the meringue. If I mix until the meringue is disappeared, the cake will deflate too much, resulting in a dense texture. 

It is better to fold in the meringue gently and stop when there are still traces of meringue scattered randomly in the batter. Pouring the batter into the cake pan slowly from a high position will give the batter a final mix naturally. 

Also, the meringue should be beaten until you can make a stiff peak when leaving up your spatula. Otherwise, it will collapse rapidly during mixing and folding and resulting in a dense cake.

Take a look at the two images below. 

Image 1: The cake on the right has a dense layer at the bottom. It is baked on the middle rack. The cake on the left, which is perfect, is baked on the lowest rack.
Image 2: The volume of the cake on the left is less. It is the result of folding the meringue until it disappears thoroughly. On the contrary, the folding of meringue for the cake on the right stop short when there are still traces of meringue visible. Hence, it has a better volume.

Variation: How to make Japanese sponge “cake-bread”

I also combine this recipe with the Japanese milk bread published in this blog to create a cake-bread loaf. You can refer to the bread recipe article to make the bread. I have added a teaspoon of cocoa powder to change the bread to a chocolate color.

To do this. Place a small dough of the bread into a loaf pan. Pour the sponge cake mix on the dough after it doubles in size. Bake as the same temperature and duration in the sponge cake recipe. 

Yield: 1 cake cut to 9 portions

Japanese Sponge Cake

Japanese sponge cake is bouncy like a piece of sponge, with the soft and delicate texture resemble cotton when you tear it open. This articles will show you every detail of how to make Japanese cotton sponge cake. (with video).

Japanese sponge cake is bouncy like a piece of sponge, with the soft and delicate texture resemble cotton when you tear it open.

Prep Time 20 minutes
Cook Time 1 hour
Total Time 1 hour 20 minutes

Ingredients

  • 100g (3.5 oz) cake flour
  • 75g (2.6 oz) melted butter
  • 60ml (4 tbsps) milk
  • Vanilla extract (optional)
  • 6 large eggs
  • 80g (2.8 oz) castor sugar

Instructions

  1. Measure the plain flour and sieve a least once. 
  2. Add the flour to the melted butter after the butter is cooled. Mixed well.
  3. Add the milk. Mix well.
  4. Lightly beat the egg yolks and add to the flour-butter-milk mixture. Mix it thoroughly. 
  5. Beat the egg whites with a hand-held mixer at low speed. 
  6. Add the sugar into the egg white after about fifteen seconds of beating.
  7. Continue beating the egg whites until it can form a stiff peak.
  8. Add a quarter of the meringue to the batter to dilute the batter so that it is easier to mix, then add the diluted batter back to the bulk of the meringue. Fold the meringue into the batter slowly until it is almost homogenous. 
  9. Line the cake pan with a large piece of baking paper. Brush the paper with some melted butter.
  10. Pour the cake mix into the pan.
  11. Gently tap the cake pan a few times to break the large bubbles.
  12. Place the cake on the lowest rack, with the hot water bath. Bake at 160 °C/320°F for sixty minutes.

Notes

If you encounter any audio / visual problem of viewing this video, you can view it from YouTube by clicking this link, which will open in a new tab.

Nutrition Information:

Yield:

9

Serving Size:

1 cake cut to 9 portions

Amount Per Serving: Calories: 187Total Fat: 10gSaturated Fat: 5gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 142mgSodium: 105mgCarbohydrates: 18gFiber: 0gSugar: 9gProtein: 5g

Japanese Sponge Cake

Items you may need for this recipe.

    84 replies to "Japanese sponge cake – How to make the most cottony and bouncy cake"

    • KP Kwan

      Hi, this is KP Kwan. I am happy to see you in this comment area, as you have read through my recipe. I am glad to reply to any questions and comments as soon as possible.

      • Gbemi

        Cant wait to make this,but first, what is a hot bath & secindly what if j dont have a hand held beater? Can it come out the same? Pls help,thanks

        • KP Kwan

          Hi Gbemi,
          1. Put the cake pan in another larger container, which contains some hot water before baking. (Please watch the embedded video at 5.06 minute).
          2. Handheld beater in basic equipment that you need to purchase to make the cake. Please buy one.
          Thanks,
          KP Kwan

          • Gbemi

            Just saw ur reply, thanks a million,will do

    • Lily

      Hi Kwan, may I know the dimension of your square cake pan?

      • KP Kwan

        I am using 8×8 inches cake pan.

    • Gloria

      Can you list the amounts in cups, tsp, tblsp etc?

      • KP Kwan

        Hi Gloria,

        Thanks for your comment.

        Since each ingredient has different density, it turns out there’s no standard conversion.

        The reason for me to use grammage is because that’s the most accurate measurement. However, you can convert all the ingredients by using the following conversion service :

        https://m.convert-me.com/en/convert/cooking/

        Hope you this is useful to you.

        KP Kwan

      • Saheefa Nadeem

        Could i use ghee instead of butter?

        • KP Kwan

          You can, but the difference is minimal.

      • Donna

        If you are wanting an American audience to try your recipes, you have to include our measurements!!!

        • KP Kwan

          Hi Donna,
          I’ve just added the measurements (in bracket) into the recipe.
          KP Kwan

        • Anji

          Can you not find a conversion table online? I live in England and just convert recipes from a ‘printed off internet page’ I keep with my cookbooks. Australian and American cup sizes differ and we English rarely use cups, we use grams or pounds and ounces.

    • Rupnarayan

      It looks so yummy. I will try to make this Japanese sponge cake.

      • KP Kwan

        Rupnarayan you are welcome. Enjoy the cake 🙂

    • Ritika

      AMAZING! it looks delicious and mouth-watering cake recipe. I will surely try this recipe on my father’s birthday. and I’m sure he would really like it a lot.

      • KP Kwan

        Hi Ritika,
        Thanks so much for trying the recipe 🙂
        KP Kwan

    • Bui

      How many eggs please?

      • KP Kwan

        6 Eggs. You can find this in the recipe.

        • Loic Thomann

          I do not see any mention of 6 eggs in the recipe. Only here.

          • Loic Thomann

            nvm my bad, it’s at the bottom in the list.

            • KP Kwan

              Haha, you got it 🙂

          • KP Kwan

            Hi Loic,
            Here are the ingredients. Six eggs are required:
            100g cake flour
            75g melted butter
            60ml milk
            Vanilla extract (optional)
            6 large eggs
            80g castor sugar

            Thanks.
            KP Kwan

    • Cirilo Howard

      i will try this at home, thank you.
      it is interesting how the cake rises without any baking powder or leavening.

      • KP Kwan

        Yes. That is how the sponge cake is. It depends on the air trapped in the egg white to raise the cake. If you add a small amount of baking powder, it will enhance it further, and that is called chiffon cake.

    • Mark Chan

      Hi, attempted your recipe. My very first cake! But what came out was exactly one third (the base) was dense and the top 2/3 was as a sponge cake should be. Could you please advise? I have photos of it and can send to you by email if a look would help with dxplanation.

      The 2 issues I see may cause this include the meringue not done to hard point, and due to our cake tin being two-part I didn’t use a water bath.

      Advise much appreciated! The taste is there.

      Mark

      • KP Kwan

        Hi Mark,
        I am not entirely sure, but trying to visualize the problem:
        1. You need to use a water bath for cooking evenly. Try to get one.
        2. The meringue should form a stiff peak, but I do not think that is the cause of having a different texture of the cake (top and bottom part).
        3. If your 2 part cake tin is not tight enough, wrap it with aluminum foil to wrap up the base, and you still can use a water bath.
        4. Not sure if this is caused by uneven mixing. Try to mix a little longer before adding the meringue.
        5. You can email me at info@tasteasianfood.com

        Regards,
        KP Kwan

        • Tiffany

          I also had this issue! The bottom 1/3 of the cake turned out like a cooked dense egg layer and the top turned out just fine, spongy. I can not figure out why this happened!

          Is this because of the water bath? I tried twice, once with hot water and the other with cold water and both times the texture was 2 different textures. Is there something wrong with the egg/flour mixture? I am certain I made stiff peaks in the meringue. Help!

          I am so confused!

          • KP Kwan

            Hi Tiffany,
            It seems that you are not the only one who has this problem. Since I have not encountered such a problem, let me make one later this week to see if I can replicate that. Will keep you updated 🙂
            KP Kwan

            • Angelica

              I also had the same exact problem! Please advise!

            • KP Kwan

              The problem you mentioned is reported by other readers too. I have revisited the recipe this weekend and will post my test result soon. I will keep you posted.

            • KP Kwan

              I have just added a section with the title Additional information – May 2020 in the text. It is highlighted with a grey background. You can get the answer to the problem you faced after I have tested the recipe again. Cheers!

    • Wai Yee

      Hi Kwan,
      I’d like to try this cake recipe. Is it possible to add some pandan leaves juice for this cake as I really love pandan flavor? If yes, how much (in gram) to add and at which stage of the cake process to do so?

      Thank you.
      Wai Yee

      • KP Kwan

        Try this:
        1. Take pandan leaves about 20g (how many pieces depends on the size of the leaves)
        2. Cut into small pieces.
        3. Add to a food processor, add the 60ml milk as in the recipe to blend it.
        4. Pour in a cloth bag or cheesecloth, drain and squeeze out the juice, and use only the pandan extract.

        • Wai Yee

          Hi Kwan,
          Thanks for your advice.

          What about if I add green tea powder? Do I use 1 tablespoon of green tea powder and dilute with the 60ml milk? Or is it necessary to add additional amount of milk for green tea powder recipe?

          Appreciate your kind advice.
          Thank you.
          Wai Yee

          • KP Kwan

            Hi Wai Yee.
            I suggest you mix a tablespoon of green tea powder with the flour and add an additional 20ml of milk.
            Thanks.
            KP Kwan

    • CK

      I tried the recipe, and it worked beautifully … until it came time to cool. After a few minutes out of the oven, the top wrinkled, and the cake sunk down. Also, the bottom of the cake was very sticky after I removed the parchment. Is this the result of underbaking, or something else? Help!

      • KP Kwan

        Hi CK,
        I suggest baking a little longer. It looks like undertake. Reduce the temperature slightly if the surface turns too dark due to the increase in baking time.
        KP Kwan

    • Lydia Marina Barbosa

      Perfectly done and with gluten free flour! I’d loved it! Thanks

      • KP Kwan

        Hi Lydia,
        Thank you for trying the recipe and happy to know that it works well.
        KP Kwan

    • Meg

      Hi,
      I made this cake today and it was big hit . Thanks a lot for the recipe .

      • KP Kwan

        Hi Meg,
        I am so glad to know that it works and everyone loves it.
        Cheers!
        KP Kwan

    • SW

      Can I use all purpose flour instead of cake flour?

      Thanks!

      • KP Kwan

        There are different names of the same thing referred to in different places. You can use either cake flour, all-purpose flour or plain flour.

    • Magdalene Wai

      I thought my cake turned out well as it did not sink. When i cut the cake half of it is like your texture but below is like custard. My oven tend to be hot so i put about 140 as the top already browned. The bottom part is like custard is it because of the temperature. My baking tray i used is the square pan so the cake became a thin layer.

      • KP Kwan

        Hi Magdalene,
        Thank you for leaving your comment here.
        I have yet to encounter any problems like what you mentioned. Is that any possibility that the water from the water bath leak into the cake? Also, it looks like the top temperature is higher than the bottom temperature. You may want to try to turn up the temperature of the bottom at lower the top temperature. Hopefully, your oven has a separate setting for the top and bottom temperatures.
        I will be likely making another sponge cake this weekend. I will leave my message here if I can find out the reason for the problem.
        KP Kwan

        • Magdalene Wai

          Thanks for your reply. Maybe I think the hot bath water must have got in thats why it seems damp below. I will try again. Thanks

          • KP Kwan

            You are welcome 🙂

    • Kelly Velasco

      Hi I’m doing the cake but when I put the egg yolks it didn’t give the the same texture as yours. Mine looks more like a mass. What should I do? Thank you

      • KP Kwan

        Hi Kelly,
        I am not exactly sure how it looks like after you add the egg. It should be the texture in the video (at 1.50 min). If it is like a mass as you mentioned, can it be the melted butter is too hot, and partially cooked the eggs? I am just guessing, but hopefully, I am right.
        KP Kwan

    • michael

      can i used 40g of sugar

      • KP Kwan

        Hi Michael,
        I have not tried to cut the sugar by half, but it is possible as the cake does not depend on the sugar to trap air and expand.
        KP Kwan

    • michael

      thanks kwan

    • Mirai Chan

      Hi, can I use an air fryer for this?

      • KP Kwan

        Hi Mirai,
        I have not tried by using an air fryer before. I am sorry I cannot give you an answer for this 🙂
        KP Kwan

    • Aish

      I tried this recipe, but it turned out very eggy and not sweet at all. I tried this recipe to the dot.

      • KP Kwan

        Hi Aish,
        The amount of sugar is one that you can increase or decrease without affecting much of the final texture. And yes, this cake contains plenty of eggs.
        Thanks.
        KP Kwan

    • Connie

      Hi KP, I just baked it the first time and it cracked on the top – how do I prevent it from happening. Other than that it is very spongy and light. I used the water bath and used 300F. I used a round tin instead of square. Do you think that matters? Thank you!

      • KP Kwan

        Hi Connie,
        The most likely reason is the top temperature is too high, or the cake is also near to the top heating element. Not all the temperature indicators are accurate. I have two identical ovens, but the indicators show about ten degrees different, after checking with an external oven thermometer.
        As for the round and square, round tin tends to crack more often based on my experience. However, I have tried to figure out the reason until today 🙂
        KP Kwan

    • Ying

      Hi KP, if I would like to make an orange flavoured cake with this recipe, how can I add in the orange juice without affecting the moisture level of the cake? And also, how would you advise on the amount of orange juice? Thank you!

      • KP Kwan

        Hi Ying,
        I have never tried the way you mentioned. However, if I attempt to make it, I will substitute all the milk with orange juice, and stir in some finely grated orange rind. I think the rind is essential because if you add more orange juice for a stronger taste, the cake will be too wet.
        KP Kwan

    • Roxy

      Hi KP,

      I’ve followed your recipe exactly but came across a few problems:

      1) When I mix in the butter it forms a very lumpy batter, I continue mixing and the lumps still don’t go away.

      2) My cake never gets as much of a rise, what could you suggest I do differently?

      Thank you!

      • KP Kwan

        Hi Roxy,
        Here are my suggestions:
        1. Add the milk (and egg) bit by bit, small batches. Mix well before adding the next batch. If you add a large amount at any time, the lumps will form.
        2. Use wire mish beater as I use in the video. Do not use the spatula to mix because it will form lumps.
        3. The meringue must be beaten until it forms peaks. If you undermix the meringue, it will not be stable and collapse while mixing with other ingredients later.
        4. Use a spatula (not wire beater this time) to combine the last 3/4 of the meringue with the flour/milk/sugar/egg. If you use wire beaten, it will break the air trap inside and deflate the cake.
        I hope one of the above is the cause, and I hope you will get a great result next time.
        KP Kwan

    • B

      Hi – I made this recipe today and I have the same complain as above. The smell and taste is very eggy, kind of like an omelette rather than a cake.
      Does not feel like a dessert. It feels like a side savory dish. Is this how it is supposed to be?

      • KP Kwan

        HI B,
        This cake has plenty of eggs! I will post another Japanese cake (castella) later today, and it is also eggy. If you prefer less egg, do try the butter cake recipe 🙂
        https://tasteasianfood.com/butter-cake/
        Best regards,
        KP Kwan

    • SK

      Hi, tried this today and baked for almost 1.5hrs… when I took it out, no crack nor shrink but I can hear like kind of sss ssss sound when I remove the parchment paper n pressing on d cake… is it undercooked? Thanks

      • KP Kwan

        Hi Sk,
        I do not know whether it is undercooked, but 1.5 hours is quite long. I suggest you bake it for one hour, which means you may need a higher temperature. The cake will become dryer if you bake it for a longer time.
        If you suspect it is underbaked, you can check the doneness by:
        1. Press the surface of the cake. It should bounce back like a sponge.
        2. Pierce a wood skewer/toothpick into it. It should come out clean.
        Thanks.
        KP Kwan

    • Jack Frey

      I have tried to make this several times and every time the cake comes out undercooked! I’ve left it at 300F for 2.5 hours and still undercooked, I’ve left it at 320 for 1.5hours another time – still undercooked.

      I am not sure how you are getting such good results when it seems the very thing causing this mess is the water, Does the water not keep the pan at 100C or lower? And if that’s the case how is it supposed to bake through ever?

      • KP Kwan

        The problem you mentioned is reported by other readers too. I have revisited the recipe this weekend and will post my test result soon. I will keep you posted.

      • KP Kwan

        I have just added a section with the title Additional information – May 2020 in the text. It is highlighted with a grey background. You can get the answer to the problem you faced after I have tested the recipe again. Cheers!

    • Beatrice

      Hi KP Kwan. Did you bake the cake in the convection oven? My oven is convention one, heat comes out only from the bottom. How can I adjust the temperature for a non convection oven? Also, if I use the round pan, what size should I use? Thank you.

      • KP Kwan

        Hi Beatrice,
        I am using an oven with top and bottom heat, no fan. I believe you can use only heat from the bottom, as you need much more heat at the bottom. However, I am not sure if it is useful to switch on the fan.
        If you use a round pan of the same diameter, the cake will be higher by about 20%. It should be fine if the side of the pan is tall enough.
        KP Kwan

    • Teresa

      Hi, may I know can I use non stick cake pan instead of aluminium cake pan? Thank you.

      • KP Kwan

        Hi Teresa,
        You can use a non-stick pan, with baking paper guarding the sides of the cake pan. I never try to use non-stick pan before, and if you do not use baking paper, I am concern the cake will not cling on to the sides while rising. You can give it a try. The reason I point out this matter is that if you are making chiffon cake, you cannot use a non-stick pan and must keep the pan oil-free to have a good rise. Sponge cake behaves closely to chiffon too, and that is why I am worried.
        KP Kwan

    • Marianne

      This was lovely. So light and fluffy. Green tea powder is a good idea for next time. Wish I could post a photo.

    • Chris

      Hi Kwan,

      If I would like to bake a smaller cake using a 6×6 square pan, should I decrease all the ingredients amount to half?

      Thanks!

      • KP Kwan

        Hi Chris,
        I will do the same thing i.e., to reduce all the ingredients by half. Also, you may need a slightly shorter time to bake.
        Thanks.
        KP Kwan

        • Chris

          Hi Kwan,

          Can you advise how long should be the baking time if to use a 6×6 square pan?

          Thanks

          • KP Kwan

            Hi Chris,
            I will go for 40 minutes, then check the doneness to decide if it has to be extended.
            KP Kwan

            • Chris

              Hi Kwan,

              Ok noted with thanks! This will be the third cake recipe I am baking in your blog. I have tried both banana and carrot cake and they turned out so good following all your steps even though I am a new baker. Hopefully this will turn out well too as this cake seems to need more skill and experience.

              Thanks

            • KP Kwan

              Hi Chris,
              Thanks for your reply and all the best!
              KP Kwan

    • Aizat

      Hi Kwan,

      Can you advice me on why my japanese cotton sponge cake rise when baking and after i take out of the oven the cake start to shrink? I tried to lower down the temp to 140oC for the next trial as the top part already brown but still im having the same problem of shrinkage. I know it should shrink a bit after baked but why it shrinked so much? Does higher temp makes the cake rise so much? Im not having dense cake problem and ive followed all the tips and precaution of making this cake.

      Thank you 🙂

      • KP Kwan

        Hi Aizat,
        May I suggest the followings:
        1. Place the cake at the lowest rack to bake, so that you can use a higher bottom temperature for baking without the concern that the surface will brown too quickly.
        2. Do not apply any oil to the sides of the pan. Let the cake cling on the oil-free sides while cooling.
        3. You can also try to leave the oven ajar after switching off the oven. Wait for ten minutes before removing the cake out from the oven. It helps to reduce the sudden change of temperature that can cause shrinking.
        I hope this is useful 🙂
        KP Kwan

    • Farida Banu

      WOW! nice cake

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