Japanese Milk Bread (Shokupan)

Whisk the tangzhong flour with the cold milk in a small saucepan until completely smooth and lump-free. Place over medium-low heat and cook, stirring constantly with a silicone spatula, for 3–5 minutes until the mixture thickens into a thick, glossy, pudding-like paste and a thermometer reads 65 C (150 F). At this temperature the starch granules fully gelatinize, and in this gelatinized state they can absorb and lock in far more water than raw starch — this is the scientific reason shokupan stays softer longer than any other bread. Remove from the heat, press a sheet of plastic wrap directly onto the surface to prevent a skin forming, and cool to room temperature.

In a stand mixer bowl, combine the bread flour, sugar, salt, and instant yeast (keep salt and yeast on opposite sides of the bowl before mixing). Add the warm milk, egg, and cooled tangzhong. Using the dough hook, mix on low speed for 2 minutes until combined, then increase to medium for 5 minutes. The dough will be shaggy and sticky at first — resist adding extra flour. It will come together as the gluten develops and the tangzhong integrates. After 5 minutes it should begin to pull away from the bowl sides.

With the mixer running on medium, add the softened butter in small pieces, about 1 tablespoon at a time, waiting for each addition to be fully absorbed before adding the next. This will take 8–10 minutes of mixing in total after the butter is all in. The dough will go through an ugly phase — looking greasy and broken — before it comes back together into a silky, elastic ball that pulls completely clean from the bowl. Increase to medium-high for the final 2 minutes. The windowpane test should be very easy to pass: a small piece stretches to nearly translucent without tearing.

Place the dough in a lightly oiled bowl, cover with plastic wrap, and let it rise at room temperature (24–26 C) for 1 to 1.5 hours, until doubled in size. Because of the tangzhong and high butter content this dough rises more slowly than a lean dough. Punching it down once at the halfway point (45 minutes) helps develop a more even, fine crumb by redistributing the yeast and redistributing gas. After the full rise, chill the dough in the refrigerator for 20 minutes to firm it up, which makes the sticky dough much easier to divide and shape cleanly.

Divide the chilled dough into 4 equal pieces. Flatten each piece into a rectangle, fold the long sides in toward the center, and roll it into a tight cylinder. Place all 4 cylinders side by side in a greased 9x5 Pullman loaf pan (or a standard loaf pan), seam-side down. For a classic shokupan dome, leave the pan uncovered. For a flat-topped Pullman loaf, slide the lid on. Cover and proof at room temperature for 1 to 1.5 hours, until the dough crests 2 cm above the rim (dome) or fills the Pullman pan 90%.

Brush the proofed loaf with cream or milk for a shiny, deep golden crust. Bake at 180 C (355 F) for 30–35 minutes for a dome loaf, or 35–40 minutes with the Pullman lid on. The loaf is done when the top is a rich, even golden-brown (no pale doughy patches), the internal temperature reads 93–96 C (200–205 F), and the sides pull away from the pan. Remove from the pan immediately and cool completely on a wire rack for at least 1 hour before slicing. The crumb will be dense and gummy if cut hot — it continues to set as it cools.