- Heat oven to 375°F.
- Cook macaroni as directed on package, omitting salt and reducing the cooking time by 2 min. Rinse macaroni under cold water; drain. Combine shredded cheeses; reserve 1/2 cup for topping.
- Melt 5 Tbsp. butter in Dutch oven on low heat. Add flour; mix well. Cook 2 min. or until hot and bubbly, stirring constantly. (Do not cook until browned.)
- Whisk milk gradually into butter mixture; cook on medium heat 5 min. or until sauce comes to boil and thickens, stirring constantly. Remove from heat.
- Add remaining shredded cheese mixture to the sauce along with the VELVEETA, blue cheese, mustard and 2 Tbsp. Parmesan; cook 3 to 5 min. or until VELVEETA is completely melted, stirring constantly. Add macaroni; mix well. Spoon into 13x9-inch baking dish sprayed with cooking spray.
- Melt remaining butter; mix with bread crumbs, reserved shredded cheese mixture and remaining Parmesan. Sprinkle over macaroni mixture.
- Bake 25 to 30 min. or until top is golden brown, and macaroni and cheese is hot and bubbly around edges.