12 tbsp unsalted butter – softened, cut into pieces
1 large egg – beaten (for egg wash)
Instructions
Warm the whole milk to 105–110°F, then whisk in the active dry yeast and let stand until foamy, 5–10 minutes.
In the bowl of a stand mixer, whisk together the all-purpose flour, granulated sugar, and fine sea salt.
Add the large eggs and the milk–yeast mixture to the dry ingredients; mix on low until a shaggy dough forms, 2–3 minutes.
Knead on medium speed until smooth and slightly elastic, 6–8 minutes. With the mixer running, add the unsalted butter a tablespoon at a time, letting each piece fully incorporate before adding the next; continue kneading until the dough is glossy, very smooth, and pulls cleanly from the bowl, 6–8 minutes more.
Scrape the dough into a lightly greased bowl, cover, and let rise at warm room temperature until doubled in size, 60–90 minutes.
Gently deflate, cover tightly, and refrigerate until thoroughly chilled and firm, 8–12 hours.
Turn the cold dough out onto a lightly greased surface, shape into a tight log, and place seam-side down in a greased 9Ă—5-inch loaf pan.
Cover and let rise at warm room temperature until the dough crowns about 1 inch above the rim and jiggles slightly when the pan is tapped, 1.5–2 hours.
Heat the oven to 375°F (190°C). Beat the egg for the egg wash until fluid, then brush the surface of the loaf gently.
Bake until deep golden brown and the center registers 190°F (88°C), 25–35 minutes; tent with foil if browning too quickly.
Cool in the pan for 10 minutes, then turn out onto a rack and cool completely before slicing, at least 1 hour.