Shape the dough
Sprinkle the cornmeal evenly over an 11-by-17-inch (28-by-43-cm) rimmed baking sheet. Place the dough on the prepared sheet. Press down on the center, and, working from the center outward, push and stretch the dough evenly to the edges of the pan. (If the dough is difficult to handle, set it aside, covered, for 10 minutes and try again.) Cover the flattened dough with a damp kitchen towel and let rise for 15 minutes.