1 tablespoon olive or vegetable oil
1 medium onion, chopped
1 large clove garlic, finely chopped
1 (26 ounce) can four-cheese flavored spaghetti sauce
1 (15 ounce) can tomato sauce
1 teaspoon Italian seasoning
2 (25 ounce) packages frozen beef-filled ravioli, divided
2 cups shredded mozzarella cheese, divided
1/4 cup chopped fresh parsley
Heat oil in 10-inch skillet over medium heat. Cook onion and garlic in oil about 4 minutes, stirring occasionally, until onion is tender. Stir in spaghetti sauce, tomato sauce and Italian seasoning.
Place 1 cup of the sauce mixture in the bottom of a 4 1/2 to 6-quart crockpot. Add 1 package frozen ravioli; top with 1 cup of the cheese. Top with remaining package of ravioli; top with remaining 1 cup cheese. Pour remaining sauce mixture over the top.
Cover and cook on LOW for 5 to 7 hours or until ravioli are tender. Sprinkle with parsley.