Omit spaghetti. Fill each sandwich, fill 1 split French bread roll (6 inch) with 3 meatballs; top with sauce and KRAFT Shredded Mozzarella Cheese. Bake in 375°F oven 5 min. or until cheese is melted.
Bake meatballs as directed, then place in slow cooker. Add sauce; cook until meatballs are done and sauce is heated through. Use the slow cooker to keep the meatballs warm while transporting to your destination.