Creating Stuffed Creamy Tomato Basil Pasta Shells can be both enjoyable and rewarding. Follow these step-by-step instructions for a successful dish:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Cook the Pasta: In a large pot, bring salted water to a boil. Add the pasta shells and cook for 8-10 minutes until al dente. Drain and set aside to cool.
3. Make the Filling: In a medium bowl, combine ricotta cheese, mozzarella cheese, Parmesan cheese, egg, basil, garlic, salt, and pepper. Mix until smooth and creamy.
4. Stuff the Shells: Using a spoon, carefully fill each pasta shell with the cheese mixture. Set aside.
5. Prepare the Sauce: In a large skillet, heat olive oil over medium heat. Add the marinara sauce and let it simmer for about 5 minutes.
6. Assemble the Dish: Spread a layer of marinara sauce on the bottom of a baking dish. Arrange the stuffed pasta shells on top, and then cover them with the remaining marinara sauce.
7. Bake: Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 5-10 minutes until bubbly and golden.
8. Garnish and Serve: Remove from the oven, allow to cool slightly, and garnish with fresh basil leaves before serving.