Step 1: Cook the Jumbo Shells - Bring a large pot of salted water to a boil. Cook the jumbo pasta shells according to package instructions until they are al dente. Drain and rinse with cold water to stop cooking. Set aside.
Step 2: Sauté the Spinach - In a skillet, heat olive oil over medium heat. Add minced garlic and sauté for about 30 seconds. Add spinach leaves and cook until wilted, about 2-3 minutes. Remove from heat and let cool slightly.
Step 3: Prepare the Cheese Filling - In a mixing bowl, combine ricotta cheese, shredded mozzarella, grated parmesan, egg, salt, and pepper. Stir in sautéed spinach mixture until well combined.
Step 4: Stuff the Shells - Preheat your oven to 375°F (190°C). Spread a thin layer of marinara sauce on the bottom of a baking dish. Using a spoon or piping bag, fill each shell with the spinach and cheese mixture and place them in the baking dish.
Step 5: Top with Sauce and Cheese - Pour remaining marinara sauce over the top. Sprinkle additional mozzarella cheese for extra cheesiness.
Step 6: Bake - Cover baking dish with foil and bake for 25 minutes. Remove foil and bake for an additional 10-15 minutes, until cheese is bubbly and golden brown.
Step 7: Serve and Enjoy - Let the stuffed shells cool for a few minutes before serving. Garnish with fresh basil leaves and serve with extra parmesan cheese.