STARTER
50 grams (1/4 c + 2 tbsp) white flour
5 grams (11/4 tsp) granulated sugar
1 gram (generous 1/8 tsp) fine sea salt
0.2 gram (pinch) instant yeast
44 grams (2 tbsp + 21/4 tsp) cold whole milk
DOUGH
500 grams (31/2 c + 1 tbsp) white flour, plus additional as needed for working with the dough
50 grams (1/4 c) granulated sugar
9 grams (11/2 tsp) fine sea salt
4 grams (11/4 tsp) instant yeast
325 grams (11/4 c + 2 tbsp) cold whole milk, plus additional for brushing the top of the dough
75 grams (1/4 c + 21/4 tsp) eggs, lightly beaten
50 grams (7 tbsp) unsalted butter, at room temperature, plus additional for the pan and brushing the top of the dough
FOR THE STARTER
1 Stir together the flour, sugar, salt, and yeast in a medium storage container. Pour in the milk. Mix with your fingers, pressing the mixture into the sides, bottom, and corners until all of the flour is wet and fully incorporated. This starter is best if covered and left at room temperature for 6 hours, then chilled in the refrigerator for 6 hours. But if the timing is better, you can also leave it at room temperature for 2 to 3 hours and then move it to the refrigerator to chill for 9 to 12 hours.
FOR THE DOUGH
1 Stir together the flour, sugar, salt, and yeast in a medium bowl.
2 Pour about one-third of the milk around the edges of the starter to release it from the sides of the container. Transfer the starter and milk to an extra-large bowl along with the remaining milk and the eggs. Using a wooden spoon, break the starter up to distribute it in the liquid.
3 Add the flour mixture, reserving about one-sixth of it along the edge of the bowl (see Mixing). Continue to mix with the spoon until most of the dry ingredients have been combined with the starter mixture. Switch to a plastic bowl scraper and continue to mix until incorporated. At this point the dough will be slightly sticky to the touch.
4 Push the dough to one side of the bowl. Roll and tuck the dough (see Rolling and Tucking), adding the reserved flour mixture and a small amount of additional flour to the bowl and your hands as needed. Continue rolling and tucking until the dough feels stronger and begins to resist any further rolling, about 15 times. Then, with cupped hands, tuck the sides under toward the center. Let rest for 5 minutes.
5 For the first stretch and fold (see Stretching and Folding), lightly dust the work surface and your hands with flour. Gently stretch the dough into a rectangle. Pinch the butter into pieces, distributing them over the top of the dough. Using your fingers or a spatula, spread the butter across the surface of the dough. (For photos of the following process, see Incorporating Add-Ins.) Roll up the dough tightly from the end closest to you; at the end of the roll the dough will be seam-side down. Turn it over, seam-side up, and gently press on the seam to flatten the dough slightly. Fold in thirds from left to right and then do 4 or 5 roll and tuck sequences to incorporate the butter. Turn the dough seam-side down and tuck the sides under toward the center. Place the dough, seam-side down, in a clean bowl, cover the top of the bowl with a clean kitchen towel, and let rest at room temperature for 45 minutes.
6 For the second stretch and fold, use the plastic bowl scraper to release the dough from the bowl and set it, seam-side down, on the work surface. Gently stretch it into a roughly rectangular shape. Fold the dough in thirds from top to bottom and then from left to right. With cupped hands, tuck the sides under toward the center. Place the dough in the bowl, seam-side down, cover the bowl with the towel, and let rest for 45 minutes.
7 For the third and final stretch and fold, once again repeat the steps for the first stretch and fold, then return the dough to the bowl, cover with the towel, and let rest for 45 minutes.
8 Butter the bottom and sides of a 13 by 4 by 4-inch (33 by 10 by 10 cm) Pullman loaf pan.
9 Lightly dust the work surface and your hands with flour. Press the dough into a 10-inch (25 cm) square and then roll into a loose tube about 10 inches (25 cm) long (see Shaping a Tube or Oval Loaf). Let rest for 5 minutes. Press the dough out again and then shape into a tight tube about 12 inches (30 cm) long. Place the tube, seam-side down, in the prepared pan. Spread some butter over the top of the dough and cover the top of the pan with plastic wrap. Let ferment at room temperature until the dough rises to about 1/2 inch (1.5 cm) from the top of the pan, 31/2 to 4 hours.
10 Position an oven rack in the center of the oven, then preheat the oven to 425°F (220°C).
11 Gently brush milk across the top of the dough and bake for 10 minutes. Lower the oven temperature to 380°F (195°C) and bake for 10 minutes. Rotate the pan and bake for 10 minutes longer.
12 Remove the pan from the oven. Carefully turn the bread out of the pan, then return the loaf to the oven and bake directly on the rack to brown the sides a bit more, about 5 minutes.
13 Transfer the bread to a cooling rack and let cool completely before slicing and eating, at least 4 hours but preferably 8 to 24 hours.
