Heat oven to 350 degrees F. Grease 13 x 9 x 2-inch baking dish. Heat oil in large skillet over medium-high heat. Add onion and peppers; cook 5 minutes. Add zucchini and garlic; cook 5 minutes, until barely tender.
Add tomatoes, sausage, Italian seasoning, salt and pepper; cook until somewhat dry, 5 to 7 minutes. Add 2 tablespoons Parmesan. Spoon half into prepared dish. Top with 1 cup mozzarella. Add remaining tomato mixture. Arrange bread sticks on top in lattice pattern, trimming to fit. Sprinkle with remaining Parmesan and mozzarella.
Bake in 350 degree F oven 25 minutes, until bread sticks are browned and filling is bubbly. Makes 8 servings.