In a deep skillet, cook 1 pound Italian sausage, ? pound ground beef, and 1 medium chopped onion, stirring constantly until meat is browned. Drain meat mixture. Cook 12 oz. penne rigate pasta, according to package directions. (I added 1 teaspoon salt and a splash of olive oil, and cooked the pasta for about 8 minutes.) Drain pasta. In your deep skillet, combine browned meat mixture, cooked pasta, a 26 oz. jar Italian sauce, and an 8 oz. can of tomato sauce. Stir until thoroughly combined. Spoon half of meat mixture into a 13-inch by 9-inch by 2-inch baking dish that has been sprayed with cooking oil. Top with half of the sliced mozzarella cheese and half of the grated Parmesan cheese. Repeat the layers, by adding the remaining meat mixture and the remaining half of the mozzarella cheese and the remaining half of the Parmesan cheese. Bake, uncovered, at 375 degrees for about 15 minutes, or until heated through and the cheeses have melted and are beginning to brown. Remove from oven and serve immediately. This casserole goes well with tossed salad greens, ciabatta bread dipped in olive oil, and a tall glass of iced tea!