Boil spaghetti according to directions on package. Drain well. (Should have about 3 cups.) Stir margarine, cheese and eggs into hot spaghetti. Pat into a 10-inch pie plate for crust. Spread cottage or ricotta cheese over crust. Brown meat and onion; drain off fat. Stir in spaghetti sauce, just enough to hold meat together (not too runny). Pour into pie shell. Bake at 350° for 20 minutes. Sprinkle cheese over top. Return to oven until cheese is melted, about 5 minutes. Take out and let stand for 10 minutes to set up. Cut in wedges to serve. Keeps well to serve as a leftover.