Preheat the Oven: Set your oven to 375°F (190°C) to prepare for baking.
Cook the Pasta: Boil the jumbo pasta shells in salted water according to the package instructions until they are al dente. Once cooked, drain them and set aside to cool slightly, ensuring they don't stick together.
Make the Filling: In a large mixing bowl, combine the chopped spinach, ricotta cheese, half of the shredded mozzarella, 1/4 cup of the grated Parmesan, garlic powder, onion powder, salt, and black pepper. Mix everything together until smooth and well combined, creating a creamy filling.
Stuff the Shells: Using a spoon, carefully stuff each cooked pasta shell with approximately 2 tablespoons of the spinach and ricotta filling. Be generous but avoid overfilling, so they seal properly.
Prepare the Baking Dish: Spread 1 cup of marinara sauce evenly across the bottom of a 9x13 inch baking dish, creating a base for the stuffed shells.
Arrange the Shells: Place the filled pasta shells in the baking dish open side up, allowing the flavors and moisture to seep in. Then, pour the remaining marinara sauce over the filled shells to coat them.
Add Cheese Toppings: Evenly sprinkle the remaining shredded mozzarella and the rest of the grated Parmesan cheese over the top of the marinara sauce for a cheesy crust.
Bake: Cover the dish with aluminum foil to prevent excessive browning. Bake in the preheated oven for 25 minutes.
Finish Baking: After 25 minutes, carefully remove the foil. Bake for an additional 10-15 minutes, or until the cheese is bubbly and turns a golden brown color, indicating it is perfectly melted.
Cool and Serve: Remove the dish from the oven and let it rest for a few minutes before serving. Garnish with fresh basil leaves for a burst of flavor and color.
Notes
Serve in individual bowls with extra marinara sauce and fresh basil for garnish.