Place milk and the bread flour in a small saucepan. Whisk until there is no more lumps. Cook this mixture over medium heat until it is thickened, about 5 minutes or less. Remove from the heat and let it cool down completely. You can also cover and keep it in the fridge to be used the next day. It can be kept in the fridge for up to 3 days
Make the dough:
If you keep tangzhong in the fridge, take it out to let it sit at room temperature for about 30 minutes or so. Mix all the dry ingredients together in a mixing bowl. Make a well in the center and pour in the wet ingredients and the tang zhong you made earlier. Use a dough hook attachment to knead the dough on speed 2 until all the crumbly dough starts to come together into one mass, it may take about 2-3 minutes for this to happen. Don't be tempted to add any liquid. You may need to stop halfway and scrape the dough off the hook and the sides of the bowl and knead again several times
Once it comes into a dough, stop the machine. The dough will not be smooth, don't worry.Cover the dough and let it rest for 20 minutes. This is an important rest that bakers refer to as an autolyse (though in our case it's a short one. Read my post above for detail)
After the rest, turn on and knead the dough again on speed 2 and knead for 1-2 minutes until it is a bit smoother. Then add the salt and sugar into the dough. Continue to knead until the dough is relatively smooth. You need to stop and scrape the dough off the hook and the bowl several times during this process. I promise it's worth the effort!
Once you have a smooth dough, turn the machine back on again to knead and increase speed to 4. Gradually add in the softened butter a bit by a bit. The dough will turn into a REAL sticky mess again because of the butter, just keep kneading and stop halfway and scrape the dough off the hook and bowl again and continue to knead until the butter is absorbed by the dough. IT WILL HAPPEN, don't worry! DO NOT be tempted to add any extra flour. You will get a shiny smooth dough that is very elastic. This may take about 10-15 minutes. The dough must pass a windowpane test, meaning, when you stretch a small amount of dough thinly, it won't break and a light can pass through
Place this dough in a lightly oiled large bowl, cover it with a clean and damp tea cloth or plastic wrap and let it rise at a warm place for about 1 hour. It may not double in size, but it will puff up some for sure.
Lightly oil your loaf pan and line your loaf pan with parchment paper with side overhanging (easier to pull the bread out later). Punch the dough down, separate it into 3 equal size balls. Cover these doughs loosely with plastic wrap and let them rest for 15 minutes. Make sure you don't skip this part of resting the dough before shaping
Roll each ball out into a rectangle shape (don't have to be exact). Fold the two long sides up and then roll it from the bottom to top. Place the seam side down in the loaf pan and repeat with the other 2 doughs. Place them next to each other. Cover with a plastic wrap
If you don't plan to bake on the same day, you can also put this shaped dough in the fridge to let the 2nd proofing happen overnight in the fridge. The next day just bring it out to let it comes to room temperature before baking
If youare going to bake on the same day, let the dough proof again for another 40 minutes or until they fill up the loaf pan. Brush the top of the dough with egg wash
Sprinkle with some white sesame seeds or other seeds of your choice if you like
Preheat oven to 375 F (190 C) for conventional oven. If you use a convection oven, lower the temperature by 20 F or 15 C. Put the pan on the middle rack and let it bake for the next 30-40 minutes depending on the oven, mine took 30 minutes. It will be golden brown on top. Remove from the oven and let it cool down in the pan for about 5 minutes and then lift the bread out and let it cool completely on a cooling rack. Enjoy and once it's cooled down completely, wrap it up with plastic wrap and it's good for about 3 days or so (it didn't last that long in our house)
2 Tbsp of sugar will make plain milk bread that you can use with fruit spread, sandwich bread, etc. If you want to make sweet milk bread, you can add up to 4-5 Tbsp of sugar.