Wash hands with soap and water.

Preheat oven to 375 °F. Lightly coat a 13x9x2 inch baking dish with cooking spray. Set aside.

Drain spinach by placing in a sieve or colander over the sink, or in a bowl and pressing with a spool to remove as much liquid as possible, or squeeze out liquid with clean hands. Place spinach in medium bowl.

Add the cottage cheese, 1 cup of the mozzarella cheese, oregano, and pepper to the spinach. Stir to mix thoroughly.

Pour half of the spaghetti sauce into prepared baking dish. Add water and stir into the mix.

Spoon about 3 tablespoons cheese mixture into each uncooked pasta shell and arrange in a single layer over top.

Sprinkle with remaining 1/2 cup mozzarella cheese evenly over sauce.

Cover tightly with foil. Bake for 1 hour or until shells are tender. Let stand 10 minutes before serving.

Try this recipe for a potluck or make-ahead dinner. If desired, refrigerate the ready-to-bake casserole.