Step 1

Place a rack in middle of oven; preheat to 400°. Whisk yeast and ½ cup warm water (about 90°) in a small bowl. Let sit until foamy, about 5 minutes.

Step 2

Mix flour, sugar, and salt in the bowl of a stand mixer fitted with the dough hook on lowest speed. With the motor running, gradually add yeast mixture and 1½ cups warm water (90°). Increase speed to the next level and mix until dough firms up into a mass around the hook (it should still be sticking to the bottom of the bowl), 8–10 minutes. Increase speed to the next level; add 34 g butter in 3 additions, mixing 30 seconds after each. Mix until dough tightens and is smooth and elastic, 12–14 minutes.

Step 3

Slap dough onto a surface with force (reserve bowl), then immediately pull some of the dough up and fold it over itself. Repeat slapping-and-folding process 2 more times, then form dough into a ball. Butter reserved bowl and place dough inside. Cover tightly with plastic wrap and drape a kitchen towel over to keep warm. Let rise near oven (a warm, draft-free spot is ideal) until nearly doubled in size (dough should spring back slowly when you poke it), 30–45 minutes (time will vary depending on the warmth of your kitchen, but be careful not to overproof). Punch down dough, divide in half, and shape each into a ball. (Find the advanced shaping tutorial here.)

Step 4

Liberally butter two 9x5x5" pain de mie pans and lids or 9x5" loaf pans. Using your hands, flatten 1 ball of dough into a 9x6" rectangle. Starting with a long end, roll up like a jelly roll into a tube. Place in a prepared pan, nudging to fit snugly. Repeat with remaining dough.

Step 5

Cover pans with plastic wrap; return to warm spot. Let sit until dough is ½" from top of pan (don’t let it rise higher or dough will deflate when you slide on the lids), 30–45 minutes. Remove plastic wrap; place lids on pans if using pain de mie. Bake bread until deep golden brown, 35–40 minutes. Turn out onto a wire rack and let cool before slicing.