In a large mixing bowl, combine ground beef, breadcrumbs, parsley, Parmesan cheese, onion, egg, garlic, salt, and black pepper. Mix until well combined.
Shape the meat mixture into small meatballs, about 1 inch in diameter. You should have approximately 24 meatballs.
For added flavor, you can brown the meatballs in a skillet over medium heat for 5-7 minutes before adding them to the slow cooker.
In the slow cooker, combine the cranberry sauce and barbecue sauce, mixing well.
Gently place the meatballs into the sauce mixture in the crockpot, ensuring they are evenly coated with the sauce.
Cover the slow cooker and cook on low for 4 hours or until the meatballs are cooked through and flavorful.
Serve warm, garnished with additional parsley if desired.