Cook the beef and onion in a 4-quart​【𝟯.𝟴 𝗟】 saucepan over medium-high heat until the beef is well browned, stirring often to break up the meat. Pour off any fat.Stir the sauce, 1 cup​【𝟮𝟯𝟳 𝗺𝗟】 mozzarella cheese and pasta in the saucepan. Spoon the mixture into a 3-quart​【𝟮.𝟴 𝗟】 shallow baking dish. Sprinkle with the remaining mozzarella cheese and Parmesan cheese. Bake at 350°F​【𝟭𝟳𝟳°𝗖】. for 30 minutes or until hot and bubbling.