Pepperoni Pizza Pasta Bake

2 pounds ground beef 1 large onion, chopped 2 jars (28 oz each) spaghetti sauce 1 package (16 oz) spiral pasta cooked and drained 4 cups shredded mozzarella cheese 8 ounces sliced pepperoni IN a large skillet, cook beef and onion over medium heat until meat is no longer pink. Drain, Stir in spaghetti sauce and pasts. Transfer to two greased 13 in x 9 in baking dishes. Sprinkle with cheese. Arrange pepperoni over the top. Bake one at 350 degrees for 25 - 30 minutes and freeze one for later.