Prepare the macaroni and cheese according to the package directions. I prepare it using half the amount of butter and use fat free milk to reduce the fat.
While the macaroni cooks, brown the beef in a skillet and drain. Add the spaghetti sauce to the meat and stir to combine.
In a 9x 13 or 11 x 7 dish, spread half of the meat mixture to cover the bottom of the pan. Follow with a layer of half of the macaroni and cheese. Repeat the layers with the remaining meat mixture and mac and cheese.
Sprinkle the mozzarella over the layers and bake at 375 degrees for 15 minutes or until hot and bubbly.