Cook the meat. Place the ground sausage in a skillet. Use a spatula to break into small pieces and cook over medium heat until there is no pink remaining.
Cook the pasta. This step is optional, but it greatly speeds up the cooking time. Boil a large pot of water and add the frozen ravioli. Cook according to the package instructions. If you want to skip the boiling step, defrost your frozen ravioli or use refrigerated ravioli before layering.
Make the filling. In a large bowl, combine the ricotta cheese, part of the mozzarella cheese, egg, salt, pepper, and Italian seasoning. Mix well.
Begin layering. Add 1/3 of the pasta sauce to the bottom of a 9x13 baking dish. Add 1/3 of the cooked sausage. Layer with half of the cooked or defrosted ravioli. Spread all of the ricotta mixture over the pasta.
Continue Layering. Add another 1/3 of the pasta sauce over the ricotta filling. Sprinkle over an additional 1/3 of the cooked sausage. Layer the remaining half of the cheese ravioli. Top with the remaining pasta sauce.
Finish layering. Add the remaining cooked sausage and top generously with shredded mozzarella cheese.
Bake, serve, and enjoy. Place the assembled ravioli lasagna into the oven and bake at 375F for 30-35 minutes until the cheese on top is melty and the casserole is warmed through. Serve with your favorite sides and enjoy!
