Switch to the flat beater and stir the starter mixture on low speed. Add 3 cups of the flour, the butter, eggs and salt. Increase the speed to medium-low and beat until smooth, about 1 minute. Add 2 more cups of the flour and beat for 2 minutes.
Switch to the dough hook. Reduce the speed to low and add the remaining flour, 1/2 cup at a time, beating until a very soft dough forms that pulls away from the sides of the bowl. Knead on low speed, adding flour 1 Tbs. at a time if the dough sticks, until smooth, springy and moist, about 6 minutes. Scrape down the sides of the bowl. Brush the bowl with a thin film of melted butter and turn the dough to coat it. Cover loosely with plastic wrap and let rise at room temperature until slightly more than doubled in bulk, 1 1/2 to 2 hours.
Line a baking sheet with parchment paper and sprinkle with the cornmeal mixture. Turn the dough out onto a lightly floured board. Divide the dough into 3 equal portions and shape each into a tight, round loaf. Place the loaves, seam side down and at least 4 inches apart, on the prepared sheet. Sprinkle the tops with flour and rub in. Cover loosely with a double layer of plastic wrap and let rise in the refrigerator for 8 to 12 hours.
Place a baking stone on the bottom oven rack and preheat the oven to 450°F.
Using a thin, sharp knife, make 3 gentle slashes across the top of each loaf. Place the baking sheet on the stone and bake for about 10 minutes, then reduce the heat to 400°F and bake until the loaves are golden brown, 20 to 25 minutes more. Let cool completely on wire racks before slicing and serving. Makes 3 small round loaves.
Adapted from Williams-Sonoma Collection Series, Bread, by Beth Hensperger (Simon & Schuster, 2002).