Step 1 Preheat oven to 450 degrees F (230 degrees C). Bring a large pot of lightly salted water to a boil. Add pasta and cook for 5 to 7 minutes or until just less than al dente; drain.
Step 2 In large saucepan, heat oil over medium heat. Add flour all at once and stir vigorously until combined. Add milk a little at a time, stirring constantly until all milk is incorporated and sauce is smooth. Stir in pepper, American cheese and tomatoes. Stir until cheese is melted and mixture is smooth (if cheese starts to stick, reduce heat). Place macaroni in a 10x15 baking dish. Pour cheese mixture over macaroni, and sprinkle with bread crumbs