Wash and trim off zucchini ends. Don't peel. Cook whole in boiling salted water until tender. Drain and chop coarsely. Cook sausage and onion together until sausage browns, stirring with a fork to break sausage. Add zucchini to sausage and onion. Add all remaining ingredients except 2 tablespoons cheese. Mix well. Turn into greased 9-inch pie plate. Sprinkle with reserved cheese. Bake at 350 degrees about 45 minutes or until firm and brown.