Crockpot Ravioli Casserole

1 T. oil
1/2 c. onion, chopped
1 large garlic clove, finely chopped
2, 26 oz. jars four cheese pasta sauce
15 oz. can tomato sauce
1 t. Italian seasoning
2, 25 oz. pkgs. frozen beef filled ravioli
2 c. shredded mozzarella cheese
fresh shredded Parmesan, optional

Spray or line crockpot. Heat oil in skillet over medium heat. Cook onion and garlic in oil about 4 minutes. Stir occasionally, until onion is tender. Stir in pasta sauce, tomato sauce and Italian seasoning. Place 1 c. of mixture in bottom of crockpot. Add 1 pkg frozen ravioli. Top with 1 c. cheese. Add other ravioli package and remaining cheese. Pour remaining sauce over top. Cover. Cook on low for 5-6 hours until cheese is melted and ravioli is hot. Top with fresh Parmesan before serving. Serve with garlic bread and salad.