Bring the water back to a boil and cook the noodles for 7 to 8 minutes. Keep the lid off the pot and heat the noodles over high heat. The water should start to bubble vigorously. Stir the noodles occasionally and cook the elbow macaroni until it's al dente. Drain water and set aside.
In a saucepan, melt butter or margarine over medium heat. Stir in enough flour to make a roux. Add milk to roux slowly, stirring constantly. Stir in cheeses, and cook over low heat until cheese is melted and the sauce is a little thick. Put macaroni in large casserole dish, and pour sauce over macaroni. Stir well.
Melt butter or margarine in a skillet over medium heat. Add breadcrumbs and brown. Spread over the macaroni and cheese to cover. Sprinkle with a little paprika.
Bake at 350 degrees F (175 degrees C) for 30 minutes. Serve.
