Heat oil in large skillet. Add zucchini, onion, tomato & garlic. Cover & cook until desired tenderness, about 10 minutes. Drain. Stir in tomato sauce & seasonings. In a 13x9-inch baking dish, place a layer of the zucchini mixture, then top with shredded cheese. Continue layers until pan is full, ending with the remaining cheese. Bake uncovered, in a 350degreesF oven, for 25 minutes. Top with shredded parmesan or Romano cheese, if desired.