Lightly coat a 6-quart slow cooker with nonstick cooking spray.
Drain and rinse the canned whole potatoes.
Add the fully cooked meatballs and potatoes to the slow cooker, spreading them evenly.
Whisk the condensed mushroom soup, beef broth, dry onion soup mix, Worcestershire sauce, garlic powder, onion powder, and black pepper until smooth.
Pour the gravy mixture over the meatballs and potatoes, gently turning to coat them.
Cover and cook on Low for 4 to 5 hours or on High for 2 1/2 to 3 hours, until the meatballs are heated to at least 165°F and the potatoes are fork tender.
Stir gently to coat everything in the gravy, then add salt to taste.
Sprinkle with chopped parsley and serve warm.