- Heat oven to 350°. Prepare jumbo shells according to package directions. Drain and rinse with cool water.
- Heat meatballs in a medium skillet with a small amount of water until heated through.
- Cut the block of mozzarella in 64 equally sized pieces that are about 2 inches long.
- Rinse and drain spinach and press all the excess water out. Combine with spaghetti sauce in a medium bowl.
- Grease a large casserole dish with nonstick spray. Take one jumbo shell and stuff with a meat ball and a small piece of mozzarella as shown in photo. Place in casserole dish. Continue stuffing the shells and placing in casserole dish.
- Pour spaghetti sauce and spinach mixture over shells and place the remaining cheese on top of shells and sauce.
- Bake shells at 350° for 15-20 minutes, or until cheese is melted.