Turn down the heat and add 2 cups of cheese by the handful, stirring until melted. Stir in peppers. Mix with pasta.
Pour into a buttered 9x9 baking dish. Toss the remaining cup of cheese with bread crumbs and sprinkle over the top, then sprinkle with a dusting of paprika. If desired, top with sliced tomato. Broil till lightly browned.