5. Repeat the layers, ending with a generous amount of Parmesan and mozzarella on top.
6. Cover and cook on low heat for 4-6 hours, or until ravioli is tender and cheese is bubbly.
7. Serve hot, garnished with extra chopped parsley.

Tips and Variations:
– For a leaner version, substitute ground turkey for the beef.
– Add spinach or mushrooms between the layers for extra veggies.
– For a touch of heat, sprinkle red chili flakes into the beef mixture.
– Leftovers can be stored in the fridge and reheated in the oven or microwave. Enjoy them the next day without any change in flavor or texture.

Indulge in the comforting essence of Italian cuisine with this slow cooker beef and cheese ravioli lasagna, perfect for feeding a crowd or enjoying a quick and easy meal.