Step 1

Line a baking sheet with parchment paper or a silicone baking mat.

Step 2

Combine the warm water, warm milk, yeast and sugar in the bowl of a stand mixer. Stir gently to combine. Let stand for 5 minutes.

Step 3

Add the salt and egg to the bowl. Use the paddle attachment to combine on low speed.

Step 4

Add both flours and mix on low speed until combined, then mix in the butter pieces.

Step 5

Switch to the dough hook and knead for 8 minutes. The dough will be very soft and slightly sticky.

Step 6

Transfer the dough to a floured work surface and knead a few times with your hands to form it into a ball. Cut the dough into 8 pieces. Shape each piece into a round ball and place on the prepared baking sheet.

Step 7

Loosely cover the dough balls with a clean kitchen towel and let rest for 15 minutes.

Step 8

Meanwhile, preheat oven to 400 degrees F.

Step 9

Combine the egg and 1 tablespoon milk in a small bowl, stirring with a fork. Remove the towel and brush the tops of the buns with the egg wash. Bake hamburger buns in the oven for 13-15 minutes, until tops are golden.