1Cook and drain pasta as directed on package.
2Meanwhile, in 10-inch skillet, cook beef and onion over medium-high heat, stirring occasionally, until beef is thoroughly cooked; drain.
3Reduce heat to medium. Stir cheese spread, milk and garlic salt into beef; continue stirring until cheese is melted and mixture is well blended. Stir in pasta and tomato. Sprinkle with Cheddar cheese; cover 2 to 3 minutes or until cheese is melted.