In a large skillet, sauté beef, onion, bell pepper, and garlic over medium-high heat until meat is no longer pink. Season with salt and pepper and drain any fat from the skillet.
Spray a large slow cooker with cooking spray. Spread 1 cup of marinara into the bottom of the prepared pot.
Top marinara with half of the ravioli, half of the cooked meat mixture, and half of the mozzarella. Add another layer of the remaining sauce, and top with the rest of the ravioli, the rest of the meat, and the rest of the mozzarella.
Cover the slow cooker with the lid and cook on high for 2-3 hours, or on low for 4-5 hours.
Sprinkle with Parmesan cheese and garnish with basil before serving.
*I used “mini” ravioli because they’re easier for the kids to eat. If you choose to use large ravioli, you may need to increase the cooking time by about 30 minutes.
The ravioli is frozen and you do not have to thaw it our before adding to the slow cooker.
You can cook this ravioli casserole on high or low depending on when you need it.
Store leftovers in a suitable container in the fridge.