Rich and creamy ricotta cheese is combined with mozzarella, beaten egg and spaghetti sauce to make a rich and filling sauce for cooked ziti. Top with Parmesan cheese and bake for a delicious, classic Italian casserole. Continue reading Rich and creamy ricotta cheese is combined with mozzarella, beaten egg and spaghetti sauce to make a rich and filling sauce for cooked ziti. Top with Parmesan cheese and bake for a delicious, classic Italian casserole.