Cook rigatoni to desired doneness as directed on package.
Meanwhile, in large nonstick saucepan, combine flour, mustard, basil and garlic powder. Gradually stir in milk with wire whisk. Cook and stir over medium-high heat for about 4 minutes or until bubbly and thickened. Reduce heat to low; stir in Cheddar and Parmesan cheese until melted.
Drain rigatoni. Stir into cheese sauce until well mixed.