01 -
Place frozen meatballs in a single layer at the bottom of a 4 to 6-quart slow cooker.
02 -
Pour the can of French onion soup over the meatballs, then sprinkle the French onion soup mix evenly on top.
03 -
Pour 1 cup (240 ml) of low or no sodium beef broth into the slow cooker. Cover and cook on high for 2 to 3 hours or on low for 5 to 6 hours.
04 -
In a small bowl, whisk together water and cornstarch until smooth.
05 -
Stir the cornstarch slurry into the slow cooker mixture, combine well, then cover and cook for an additional 10 minutes.
06 -
Sprinkle shredded mozzarella cheese over the meatballs, cover and cook until the cheese is melted.
07 -
Serve hot with mashed potatoes, egg noodles, or garlic bread and garnish with fresh thyme if desired.