Spray the slow cooker insert with nonstick cooking spray to prevent sticking.

Add approximately 30-35 frozen meatballs directly into the slow cooker.

In a separate bowl, whisk together reduced-sodium beef broth, brown gravy mix, onion soup mix, ketchup, and Worcestershire sauce until fully combined.

Pour the mixture over the meatballs, covering them thoroughly.

Cover the slow cooker and cook on LOW for 5-6 hours.

Create a cornstarch slurry by mixing cornstarch with cold water, then add it to the slow cooker and cook for an additional 10 minutes.

Serve hot with gravy over mashed potatoes or egg noodles and garnish with chopped parsley.