Cook elbow macaroni according to package directions. Drain.
Meanwhile, cut up butter, American cheese, and sharp cheese into 1 inch squares for easy melting. Separate butter and cheeses into two equal size portions.
Begin with one of the butter and cheese portions, microwave on 50% power for 7 minutes. Remove from microwave and stir well. Add second portion of butter and cheese to melted mixture. Microwave an additional 7 minutes on 50% power. Remove and stir well.
Pour cheese mixture over cooked macaroni and stir until noodles are coated with butter and cheese mixture. Allow to stand for 10 minutes before serving.