COOK pasta as directed on package, omitting salt and adding vegetables to the boiling water for the last 3 min.
MEANWHILE, microwave cream cheese and milk in microwaveable 2-cup measuring cup on HIGH 1 min.; stir until cream cheese is melted. Stir in sour cream and basil.
DRAIN pasta mixture; return to saucepan. Add cream cheese sauce and 1/2 cup shredded cheese; toss to coat. Top with remaining cheeses.