Making spinach stuffed shells can be straightforward if you follow these easy steps:

1. Preheat the Oven: Start by preheating your oven to 375°F (190°C).
2. Cook the Pasta: Boil a pot of water and cook the jumbo shells according to package instructions until al dente. Drain and set aside.
3. Prepare the Filling: In a large bowl, combine ricotta, 1 cup of mozzarella, Parmesan, chopped spinach, salt, pepper, garlic powder, and parsley. Mix until well blended.
4. Fill the Shells: Take each cooked shell and fill it generously with the spinach and cheese mixture.
5. Prepare the Baking Dish: Spread a thin layer of marinara sauce on the bottom of a 9×13 inch baking dish.
6. Arrange the Shells: Place the filled shells in the baking dish, side by side. Pour remaining marinara sauce over the top and sprinkle with extra mozzarella if desired.
7. Bake the Dish: Cover the dish with aluminum foil and bake in the preheated oven for 25-30 minutes. Remove the foil during the last 10 minutes of baking to allow the cheese to turn golden and bubbly.
8. Rest Before Serving: Allow the dish to rest for 10-15 minutes after baking for easier serving.

These simple yet effective steps will guide you in creating deliciously stuffed shells that will impress friends and family alike!