Preheat oven to 350 degrees F (175 degrees C). Butter a 2 quart casserole dish.
Bring a large pot of lightly salted water to a boil. Add macaroni and cook for 8 to 10 minutes or until al dente; drain. Transfer to prepared casserole dish and lay cheese slices over macaroni. Sprinkle with paprika.
Melt butter in a small saucepan over medium heat. Add milk and flour, stirring until it thickens. Stir in salt and pepper and pour over macaroni and cheese.