spread in single layer in a 9-inch square baking pan. Bake vegetables (using both oven racks) at 500� for 15 to 20 minutes or until vegetables are lightly browned, stirring corn and switching pan positions in oven halfway during cooking time. Let cool. Combine ricotta cheese, cumin, and salt; stir well, and set aside. Place salsa in a fine wire mesh strainer; drain excess liquid from salsa. Place in a small bowl and set aside. Arrange 9 tortilla quarters in bottom of a greased 9-inch square baking dish, arranging to fit and cover bottom completely. Spread 2/3 cup salsa over tortillas. Arrange 2 cheese slices over salsa. Spoon half of ricotta mixture evenly over salsa. Top with half of zucchini and corn. Repeat layers once. Top with remaining tortillas, remaining salsa, and remaining cheese slices. Cover with aluminum foil, and bake at 400� for 30 minutes or until thoroughly heated. Let stand 5 minutes before serving. Serve with toppings, if desired. ----