Preheat oven to 350 degrees. Spoon 1/3 of the pasta sauce into a 13 by 9 inch baking dish. Place half the ravioli on top of the sauce in a single layer - squeeze them if necessary. Sprinkle with the cooked sausage, the spinach and half the mozzarella. Layer on the remaining ravioli. Top with the remaining sauce, remaining mozzarella and Parmesan. cover with foil and bake for 20 minutes. Uncover and bake until bubbling, 5 - 10 minutes more.
Quick Tomato Sauce
In a large skillet heat 2 tablespoons of olive oil. Saute 2 minced garlic cloves for 1 minute. add 1/4 cup chopped onion if you like. Add 28 oz can diced tomatoes with all their juices. Bring to a boil, reduce heat and simmer 20-25 minutes. Season with S & P and stir in some chopped fresh basil, Keeps in the refrigerator for 3 days or frozen for about one month.