To Make Yudane
In a bowl, mix bread flour with boiling water. Mix well until well combined.
Cover with cling wrap and set aside or refrigerate for 4-8 hours. This is best prepared the day before you intend to make the bread.
Remove yudane from the refrigerator and set aside for about 30 mins or until it reaches room temperature before using.
To Make Shokupan
Add all ingredients (except butter) into the stand mixer bowl. Tear yudane into small pieces and add into the bowl as well.
Using a dough hook, knead the dough for 3 mins on low speed to bring all ingredients together.
Add in butter and continue to knead for another 20-25 mins, stopping a few times in between to scrape down the dough from the sides of the bowl and dough hook to make sure everything is evenly mixed and kneaded.
To see if the dough is ready, do the windowpane test. Pinch a small amount of dough and hold it between both your thumbs and first two fingers, and gently stretch the dough apart. If the dough is properly kneaded, it should stretch (without tearing or breaking) into a thin membrane that you can see through.
Place the kneaded dough into greased bowl and cover for first proofing. Set aside to let it rise for 45-60 mins or till double in size.
Use your knuckle to make a depression in the middle of the dough. Then, remove dough from the bowl and transfer to a floured surface. Divide into 3 portions and roll them into balls.
Roll out one dough ball with a rolling pin into a long strip and roll it up like a “Swiss roll” and seal the seam. Roll out the dough again vertically to another long strip and roll dough up like a “Swiss roll” again. Seal the seam at the end and place the sealed seam at the bottom of the bread pan. Continue with the other 2 dough balls.
Let the dough rise again for another 50-60 mins or until it reaches the pan’s rim.
Preheat oven at 190˚C for 15 mins prior to baking.
Brush beaten egg on dough surface before baking bread for 30 mins or till the top turns golden brown.