To a large pan on the stove over medium high heat, add in the sausage and break it up. Cook it thoroughly. Once cooked remove any excess grease in the pan, stir in the pasta sauce. Add a little water in the sauce jar and put the lid on top shake well then the pour into the pan. Stir well .
Spray a slow cooker with non stick spray then add in 3/4 cup of the meat sauce mixture to the bottom of the slow cooker, add in the raviolis, pour the remaining meat sauce mixture on top stir. Sprinkle the mozzarella on top. Place the lid on and cook on LOW for 2 hours or HIGH for 1 hour. Enjoy!