In the bowl of a stand mixer fitted with a dough hook, combine all the ingredients listed for the main dough, excluding the butter, including the tangzhong.
350 g bread flour, 15 g milk powder, 7 g instant dry yeast, 7 g salt, 1 whole egg + 1 egg yolk, 80 g whole milk, 20 g honey, all the tangzhong
Knead the dough on low to medium speed for about 10 minutes.
Gradually add the cubed butter to the dough, one cube at a time, while continuing to knead.
65 g unsalted butter
Continue kneading for another 10-20 minutes or until the dough passes the window-pane test – it should be smooth, elastic, and able to be stretched thinly without tearing.
Gently shape the dough into a round, and place it in a lightly oiled baking bowl.
Cover the bowl with plastic wrap and let the dough proof for about 90 minutes, ideally at around 77°F (25°C), until it doubles in size.