Spray 4 large sheets of heavy-duty foil with cooking spray; top with chicken, Italian seasoning and vegetables. Fold to make 4 packets.
Grill 15 min. or until chicken is done. Cut slits in foil to release steam before carefully opening packets.
Top ingredients (still in packets) with VELVEETA. (No need to refold packets to seal.) Grill 5 min. or until VELVEETA is melted.