1Cook and drain macaroni as directed on box. Return to saucepan; cover to keep warm.
2Meanwhile, heat oven to 375°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. In 2-quart saucepan, heat whipping cream, mustard, salt and red pepper to boiling. Reduce heat; stir in Cheddar cheese with wire whisk until smooth.
3Pour sauce over macaroni. Stir in tomatoes and onions. Pour into baking dish. In small bowl, mix Parmesan cheese and bread crumbs. Stir in oil. Sprinkle over top of macaroni mixture.
4Bake uncovered 15 to 20 minutes or until edges are bubbly and top is golden brown.