• Mix Preferment – Combine all of the preferment ingredients in a bowl and mix until fully incorporated. Cover and let rest at room temperature (70–75°F / 21–24°C) for about 16 hours, or until bubbly and active.
• Make Tangzhong – In a small saucepan, combine the flour and milk and whisk until smooth. Cook over medium high heat and whisk constantly until the mixture forms a thick, smooth, shiny paste. Immediately transfer into a bowl and place a piece of plastic wrap directly over the surface to prevent a skin from forming. Let cool to room temperature before mixing the dough.

• Prepare The Eggs – In a small bowl, whisk together 2 whole eggs and 3 egg yolks until completely combined. Weigh out 110 g (½ C) of the mixture for the dough. Reserve the remaining egg mixture for the egg wash.

• Mix The Dough – When the preferment is ready and the tangzhong has cooled, add the bread flour, sugar, salt, tangzhong, preferment, and 110 g of the prepared egg mixture to the bowl of a stand mixer.
  • Mix on speed 1 for 2 minutes until everything is combined.
  • Increase to speed 3 and mix for 5 minutes.
  • Increase to speed 5 and mix for 2 minutes.

Reduce the mixer speed to speed 2 and add the room temperature butter 1 Tbsp at a time, allowing each addition to fully incorporate before adding the next. This should take 8-10 minutes.

Once the butter has been incorporated:

• • Mix on speed 4 for 10 minutes.
  • Finish on speed 6 for 3-5 minutes, or until the dough is smooth, elastic, and passes the windowpane test. *

• Bulk Ferment – Transfer the dough in a lightly oiled bowl or container with room to expand. Cover and let ferment in a warm place for 5-6 hours, until the dough has increased to just under double in volume. Refrigerator overnight.

• Shape – The next morning, gently deflate the dough and turn out onto a lightly floured work surface. Divide the dough into 4 equal 135 g pieces and fold each corner into the middle to form a rough ball. Cover and let rest for 15-20 minutes. Flatten each piece into a 4-inch square. Starting from one edge, roll the dough up tightly into a log, pinching the seam closed. Roll gently to extend each log to approximately 4 inches long. Place into an oiled 4” x 8” loaf pan.

• Proof – Cover and let proof in a warm area of the house for about 5 hours or until the dough has risen to fill ¾ of the pan. To check for readiness, lightly flour a fingertip and gently press the side of a roll. The indentation should slowly spring back but remain slightly visible. If it springs back immediately, continue proofing.

• Bake – About 1 hour before you are ready to bake, preheat the oven to 350°F/176°C. Whisk together the egg wash ingredients and gently brush the top of the loaf. Bake for 20-25 minutes, until the top is golden brown and the internal temperature reaches 200°F/93°C. Allow the loaf to cool in the pan for 5–10 minutes before removing from the loaf pan and placing on a wire rack to cool completely.