1. Place an oven rack on lowest position and preheat to 500°F.
2. On a lightly floured surface, roll dough into a 14-inch square. Generously sprinkle a baking sheet with cornmeal. Place dough on sheet.
3. Drizzle 1 1/2 tsp. oil and scatter scallions on dough, leaving a 1/2-inch border. Top with zucchini and sprinkle with salt and pepper.
4. Bake until crust is crisp, about 13 minutes. Top with Parmesan and drizzle with remaining oil. Cut into 8 slices. Top with mint. Serve.