Preheat the oven to 325oF. Grease an 11x7-inch baking dish. Wash and trim the zucchini (do not peel). Grate them and set aside. Sauté the sausage and onion in a skillet until the sausage is completely cooked. Drain off the fat and set the mixture aside. In a large mixing bowl, beat the eggs until frothy, then add the parmesan cheese, bread crumbs, basil, oregano, salt, pepper, garlic, sausage mixture and shredded zucchini. Spread the ingredients evenly in the baking dish. Bake for 25 minutes. Remove from the oven, sprinkle cheddar cheese on top, and continue baking for 15 minutes. Cool slightly and cut into 1 ½ -inch squares.