In skillet, brown hamburger, onion, salt and pepper; drain off the grease. Sprinkle meat with flour. Add brown gravy, tomato sauce and sugar. Mix in 2 cups cooked noodles and 1 cup zucchini. Pour into 1 1/2 quart dish. Cover. Bake at 350 degrees 45 to 50 minutes. Garnish with Parmesan cheese. Serves 4.