1 lb frozen spinach, drained well and then finely chopped
¼ tsp nutmeg
1 tsp lemon zest
1 tsp salt
½ red pepper flakes (optional)
2 cups tomato sauce
½ + ½ c parmesan cheese
Preheat oven to 400 F.
Bring a large pot of water to a boil. Cook shells for about 6 minutes or just shy of being al dente. Drain in a colander and immediately rinse with running cold water to stop the cooking.
While the shells cool, assemble the filling and prepare baking dish.
In a large 9x13" baking dish, evenly spread out about 1 cup of the tomato sauce - the whole bottom of the pan should be coated liberally.
In a large bowl, add the ricotta cheese, cottage cheese, spinach, egg, nutmeg, lemon juice, salt, pepper and red pepper. Stir until completely combined. Taste and adjust seasoning as needed.
Fill each shell with a generous 1-2 tbsp of filling. Don't over fill, or else all the cheese will ooze out while the shells bake in the oven.
Line the shells up in rows in the pan. Top with the remaining tomato sauce so all the shells are covered. Sprinkle evenly with mozzarella cheese and remaining parmesan cheese. Cover with aluminum foil and baked for about 40 minutes or until warmed through.
Remove foil and bake under the broiler for another 3-5 minutes or until cheese is golden brown on top. Serve warm!