4½ tsp. instant (rapid rise) yeast
¾ cup plus 2 2/3 cup warm water, divided (105-115˚ F)
¼ cup granulated sugar
1 tbsp. salt
3 tbsp. unsalted butter, at room temperature
9-10 cups all-purpose flour
3-4 tbsp. unsalted butter, melted (for brushing)
To make the dough, dissolve the yeast in ¾ cup of warm water in a large mixing bowl (use your mixer bowl if kneading with a stand mixer and use the dough hook). Stir in the sugar, salt, remaining 2 2/3 cups water, butter, and 5 cups of the flour. Mix (on low speed) until a dough begins to come together. Gradually add in the remaining 4-5 cups of flour about ½-1 cup at a time at first, more gradually with the last cup, until the dough is smooth and slightly tacky but not sticky. Continue to knead about 6-8 minutes, until a smooth ball of dough has formed.
Transfer the dough to a lightly greased large bowl, turn once to coat, and cover with plastic wrap or a clean kitchen towel. Let rise in a warm place until the dough has nearly doubled in bulk, about 60-90 minutes.
Turn the dough out onto a lightly floured work surface and gently punch down to deflate the dough. Divide into two equal portions. Press one portion of dough into a rectangle, about 9 x 15 inches. Starting on a short end, roll the dough up tightly into a log and pinch the seam shut. Roll the ends under the loaf. Transfer to a greased 9 x 5-inch loaf pan and press down gently to reach the sides of the pan. Repeat with the second portion of dough. Cover the pans loosely with a clean kitchen towel and let rise once more until nearly doubled, about 30-45 minutes.
Place an oven rack in the lowest position and preheat the oven to 400˚ F. Just before baking, lightly brush the tops of the loaves with some of the melted butter. Bake for 15 minutes. Rotate the pans 180˚ and continue baking until an instant read thermometer reads 190˚ F in the center of the loaf, about 15-18 minutes more. (If the tops of the loaves reach your desired golden brown before the baking time is complete, cover the tops loosely with foil to prevent over-browning.) Transfer the pans to wire racks to cool. Let cool briefly, then turn the loaves out onto the racks. If desired, brush lightly with additional melted butter. Let cool completely.