Preheat the oven to 400 degrees F (205 degrees C). Place sliced onion and squash in a roasting pan. Sprinkle with rosemary, salt, pepper, and 2 tablespoons of olive oil; toss to coat.
Bake in the preheated oven for 20 minutes, or until onions are lightly browned and squash is tender; set aside.
Increase oven temperature to 450 degrees F (230 degrees C).
Roll each ball of dough into an 8-inch round on a lightly floured surface. Place each round on a baking sheet sprinkled with cornmeal; distribute squash mixture over the two rounds and bake in the preheated oven for 10 minutes, checking occasionally, or until the crust is firm. Sprinkle with cheese and remaining tablespoon olive oil. Cut into quarters, and serve.