Japanese milk bread is the fluffiest, softest bread you can find.
Mix the bread flour and water in part 1) in a small pan, heat it up slowly over low heat.
When the slurry starts to become thicker, you can draw lines while stirring it. When this happens, remove it from heat.
Mix the water and flour in part 2 together, mix it for half a minute and set aside to autolyze for at least half an hour.
Add the TangZhog and rest of the ingredients in part 2 (except butter) into the flour/water mixture. Mix with a dough hook for eight to ten minutes.
Add butter and mix for another two minutes or until you can stretch the dough to form a semi-translucent film without breaking it.
Cover the dough with a kitchen towel or cling film. Let the dough ferment at room temperature until it doubles in size. If you poke your finger into the dough at this stage, a dent will remain.
Punch down the dough. Place the dough on a working surface. Portion the dough and divide it into pieces of uniform weight.
Shape each portion into smooth, round balls. Let the dough rest on the working surface for ten minutes to let the gluten relax.
Roll out the dough as thin as possible, and then roll it up like making the Swiss roll. Place them in an oiled bread pan.
Cover it with a damp cloth or cling wrap to retain moisture.
Leave them in a warm place until it doubles in bulk.
Apply some egg wash on the surface. Bake at 180°C/350°F for 25 minutes or until the crust turns golden brown.