*Methods :
Preheat oven 375°. Combine spinach, ricotta and cream cheese, salt, pepper and nutmeg in a large bowl. In a microwave-safe dish, heat the garlic and olive oil for 20 seconds in the microwave. Add the garlic and oil to the spinach/cheese mixture.
Mix well. Pour ⅔ of the marinara sauce (2 cups) into the bottom of a 9″x13″ baking dish. Using a teaspoon, fill each shell with the spinach/cheese mixture. Place stuffed shells (open side up) in pan. Cover the mold with aluminum foil and bake at 375° for 25 minutes.
Remove foil and sprinkle breadcrumbs and Parmesan over shells. Continue cooking (uncovered) for 10 minutes until the breadcrumbs are golden brown. Remove from the oven and let rest for a few minutes before serving. Just before serving, heat the rest of the marinara sauce and pour over the shells. Add additional Parmesan if desired.