1Saute onions in olive oil until soft. Transfer to bowl and set aside.
Cook Pasta according to box directions and drain.
2Add all ingredients (except the mozzarella cheese) to the bowl. Stir until well mixed. Pour into a oiled 7x11 casserole dish. Top with mozzarella cheese. Cover and bake for 30 minutes. Uncover and bake for about 15 minutes until brown and bubbly.