First, combine the beef broth with the cornstarch to make a slurry then sit it to the side.
Now, in a bowl combine the cream of mushroom, onion soup mix, Worcestershire sauce then mix in the beef broth and cornstarch. Mix everything until it's smooth.
Next, in the crockpot add the frozen meatballs and pour the sauce right over the top. Cover the crockpot and cook on high for 2.5 hours or low for 5-6 hours. Stir halfway through the cooking time.
When the meatballs are finished before serving add in the heavy cream and mix everything together. Serve over noodles, mashed potatoes or any side dish of your choice.