1. Cook macaroni al dente following package directions. Drain and set aside.
2. In a saucepan, melt butter over medium heat. Add flour, salt and pepper, and stir until smooth. Slowly add milk and continue stirring until mixture begins to boil and thicken.
3. In a lightly greased 9 x 13 inch baking pan, spread half of cooked macaroni and sprinkle with half of cubed Velvetta cheese and half of shredded mozzarella cheese. Pour half of milk mixture on top. Repeat with a second layer and sprinkle bread crumbs on top.
4. Bake in a preheated, 350-degree oven for 35 to 45 minutes, or until hot and bubbly. If desired, broil for 1 or 2 minutes to toast bread crumbs.