Preheat oven to 400º F and spray a 2.6 quart 8"x8" baking dish with cooking spray.
In a skillet, cook and crumble the Italian sausage until browned and cooked through. Drain any excess fat and set aside.
Spread 1 cup of the sauce on the bottom of the prepared baking dish, followed by 1/2 of the cooked sausage, half of the ravioli and 1/3 of the cheese. Repeat the layer again and then top with the remaining sauce and mozzarella cheese.
Cover with foil and bake for 45 minutes, until heated through and cheese is bubbly.
Serve with shredded parmesan cheese and parsley/basil if desired.