Stir the crushed tomatoes, tomato paste, onion, garlic and seasonings together in a bowl. Pour over the ravioli and stir to coat all the ravioli with sauce.
Cook on high for 3 hours or low for 5 hours.
About 20 minutes before you're ready to eat, sprinkle the ravioli with Mozzarella.
Recipe by Eat at Home at https://eatathomecooks.com/ravioli-in-the-slow-cooker/