1. Bring a large pot of salted water to a boil and cook the jumbo pasta shells until al dente according to package directions. Drain carefully and let them cool enough to handle.

2. Preheat the oven to 375°F and spread about 1 cup of marinara sauce over the bottom of a 9×13-inch baking dish.

3. In a large mixing bowl, combine the ricotta cheese, 1 cup of mozzarella cheese, 1/2 cup of Parmesan cheese, egg, minced garlic, chopped basil, salt, and black pepper until smooth.

4. Spoon the ricotta filling into each cooked shell and arrange the filled shells in the prepared baking dish.

5. Spoon the remaining marinara sauce over the shells, then sprinkle the top with the remaining 1 cup mozzarella cheese and remaining 1/4 cup Parmesan cheese.

6. Cover the dish loosely with foil and bake for 25 minutes.

7. Remove the foil and bake for another 10 minutes, or until the cheese is melted and the sauce is bubbling.

8. Let the shells rest for 5 minutes before serving.