Step 1

In a bowl, mix active sourdough starter, flour, sugar, and cold milk. Cover and rise in a warm spot for 4 hours. You want the levain to be active but not overly sour and liquid.

Step 2

Mix flour and milk in a small pot. Heat up over medium heat. Stir until the mixture thickens and reaches a temperature of 150°F/65°C.

Step 3

Transfer to a clean bowl. Cover with plastic wrap that is touching the entire surface of the tangzhong. Cool to room temperature.

Step 4

Add all ingredients (except salt and butter) to the bowl of your stand mixer fitted with a dough hook. Mix until the dough comes together. Cover, and autolyse for 30 minutes.

Step 5

Add the salt, and knead at medium speed for 10 minutes. At this point, the dough should be tacky but not sticking to the fingers.

Step 6

Slowly add in cubed, softened butter. Continue kneading at medium speed for 15-25 minutes until your dough passes the window-pane test. Read more about the Window-Pane Test in this post.

Step 7

Transfer the dough to your work surface and divide it into four equal pieces. Roll into seamless rounds, cover, and rest for 10 minutes.

Step 8

With a rolling pin, roll each round into an oval shape about 8 in/20 cm long. Grab one of the short sides of the oval and roll it up like a roulade. Repeat on all four pieces - cover and rest for 10 minutes.

Step 9

With the seam side up, use a rolling pin to flatten each dough piece into long ovals again. Shape the ovals into roulades as you did previously. Transfer to a greased 10-inch bread pan.

Step 10

Cover the bread pan and proof in a warm spot, ideally at 78°F/25°C, for 8-12 hours or until the dough fills up about 85% of the tin.

Step 11

Preheat your oven to 355°F/180°C.

Step 12

Bake the milk bread for 30-35 minutes, until golden brown. Cover the surface with aluminum foil if it browns too quickly—the internal temperature when finished: 200°F/95°C.

Step 13

Take the bread out of the bread tin and brush the surface with melted butter (optional). Transfer to a wire rack and cool completely before slicing.