Cook macaroni according to the package directions. Drain.
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.