Position racks in upper and lower thirds of oven; preheat to 475°F. Coat 2 baking sheets with cooking spray.
Combine broccoli, corn, mozzarella, ricotta, scallions, basil, garlic powder, salt and pepper in a large bowl.
On a lightly floured surface, divide dough into 6 pieces. Roll each piece into an 8-inch circle. Place a generous 3/4 cup filling on one half of each circle, leaving a 1-inch border of dough. Brush the border with water and fold the top half over the filling. Fold the edges over and crimp with a fork to seal. Make several small slits in the top to vent steam; brush each calzone with oil. Transfer the calzones to the pre- pared baking sheets.
Bake the calzones, switching the pans halfway through, until browned on top, about 15 minutes. Let cool slightly before serving. Healthy Heart Variation: To reduce saturated fat even further, use nonfat ricotta in place of the reduced-fat ricotta. 334 calories, 2 g saturated fat