Place the beef shanks flat in the bottom of your slow cooker insert.
Sprinkle the packet of dry onion soup mix evenly over the top of the beef.
Pour the beef broth around the sides of the beef shanks until the meat is partially submerged.
Cover with the lid and cook on LOW for 7 to 9 hours (or HIGH for 4 to 5 hours) until the beef is fork-tender and pulls apart effortlessly from the bone.
Carefully transfer the meat to a serving platter and spoon the rich gravy from the cooker over the top before serving.