Add parmesan rind, crushed tomatoes, and beef broth and stir until well combined. Add the short ribs back to the pot. Bring to a boil, then lower heat to a simmer, and cover. Let the short ribs simmer for 2-3 hours until the meat is tender.
Remove the short ribs from the sauce. Remove the meat from the bones, discard the bones, and use two forks to shred the meat. Return the meat to the sauce and stir until well combined.
Serve the ragu over rigatoni with grated cheese and chopped parsley.