Saute sausage, onion, and garlic until sausage is well done. Drain fat. In a bowl, beat eggs until frothy, then stir in zucchini, Parmesan, bread crumbs, seasonings, and the sausage mixture. Pour into a greased 11x7-inch baking dish, smooth the top, and bake at 375 degrees F for 25 minutes. Sprinkle grated Cheddar on top and bake for 15 minutes longer.