Thaw ragu and meatballs (microwave or stovetop). Dice half an onion and saute in a pot until soft. Add ragu and meatballs, simmer 10-15 minutes until heated through.
Boil pasta to package directions. Drain.
Serve pasta topped with the ragu and meatballs. Shred Parmesan over the top. Steam carrots alongside if desired.