Creating Spinach and Ricotta Stuffed Shells can be easy and fun if you follow these clear instructions:

1. Preheat the Oven: Start by preheating your oven to 375°F (190°C).
2. Cook Pasta: In a pot of boiling salted water, cook the pasta shells according to package instructions until al dente. Drain and set aside.
3. Prepare Filling: In a large mixing bowl, combine ricotta cheese, chopped spinach, mozzarella cheese, Parmesan cheese, beaten egg, garlic powder, and Italian seasoning. Season with salt and pepper, mixing until well combined.
4. Fill Shells: Spoon a generous amount of the cheese and spinach mixture into each cooked shell.
5. Layer Sauce: Spread half of the marinara sauce onto the bottom of a baking dish. Place the stuffed shells on top, then cover with the remaining sauce.
6. Bake: Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the sauce is bubbly and the edges are slightly golden.
7. Cool and Serve: Once done, allow the dish to cool for a few minutes before serving. Garnish with fresh basil leaves, if desired.

These steps will guide you toward creating an incredible dish that both you and your family will love.