2½ t dry active yeast ½ c whole milk , warm (+/-110F/45C) 2¼ c unbleached all-purpose flour 6 T unsalted butter, cut into bits 3 T granulated sugar ½ t table salt or 1 t coarse salt 2 large eggs
In smallish bowl, whisk yeast into milk, then stir in 1 c of flour. Cover with plastic wrap and set aside.
Put butter, sugar, and salt in your food processor (with the metal blade on). Pulse -- scraping the sides as needed -- until all is soft and smooth. Add eggs, one at a time, and whiz until fully mixed (this may look curdled, do not freak out). Add 1¼ c flour and the resting sponge, scraping down sides as needed. Pulse until you get a soft, smooth dough and then whiz for 15 seconds.
Drop the dough (which will be sticky at this point) to your floured work bench and knead until smooth and elastic.
Butter an 8½"x4½"x2½" loaf pan; line the bottom with parchment (baking? kitchen?) paper, then butter the parchment. Press dough into a 9"x5"rectangle (short end facing you). Fold each long side +/-1" toward the middle; press firmly to seal. Fold the top half of the dough toward the middle. Fold the bottom half of the dough up past the seam; pinch seam to seal. Place dough in the pan, seam side down. Flatten the dough top with your palm so it fills the pan evenly. Cover the pan with buttered plastic wrap, let the dough rise to about 1" (2½cm) above the pan rim. Adjust oven rack to center position and heat the oven to 350F while the dough is rising.
Using a razor blade or sharp knife, slash the dough down the center, leaving about 1 inch unslashed at either end. Bake until golden brown, about 40 minutes. Transfer pan to wire rack; let cool 5 minutes. Turn the loaf out of pan onto rack; let it cool to room temperature on its side.