Place frozen meatballs in a slow cooker; set aside.
Make gravy according to package directions; stir in cranberry sauce, mustard and cream. Stir until well blended; pour over meatballs and stir to coat evenly.
Cover and cook on low setting for 4 to 5 hours, or on high setting for 2 to 3 hours.
To serve, use a slotted spoon to remove meatballs to a serving dish. Sprinkle with dried cranberries and minced parsley, if desired.