1In a pot, combine 60 grams of whole milk and 27 grams of water. Add 20 grams of bread flour and whisk until the mixture thickens.
2In a separate bowl, combine 320 grams of bread flour, 35 grams of sugar, and 7 grams of salt. Whisk together.
3Heat 120 grams of whole milk to 95 degrees in the microwave and add 9 grams of instant yeast.
4In a stand mixer with a dough hook, add the dry ingredients, then slowly add the milk and yeast mixture on low speed.
5Add the tangzhong paste, one whole egg, and one egg yolk. Increase the speed to medium-low.
6Gradually add 42 grams of butter and let the mixer knead the dough for 5-8 minutes.
7Gently fold the dough in on itself, then rub it in a circle on a work surface until smooth and round.
8Place the dough in a greased bowl, cover with a damp towel, and let it rise in a warm place (like a turned-off oven with the light on) for an hour and a half.
9Divide the dough into 6 equal pieces, shape them into balls, and place them evenly spaced on a baking sheet.
10Let the dough rise at room temperature for 1-2 hours or until doubled in size.
11Brush the buns generously with egg wash, then bake at 375°F for 16-18 minutes.
12Brush the baked buns with melted butter or brown butter.