Preheat your oven to 375°F (190°C).

Cook the jumbo pasta shells according to the package instructions until they are al dente. Drain and set aside.

In a large mixing bowl, combine ricotta cheese, cooked ground beef, egg, Italian seasoning, and half of the mozzarella cheese. Season this mixture with salt and pepper to taste.

Generously stuff each pasta shell with the ricotta-beef mixture.

In a baking dish, spread a thin layer of marinara sauce on the bottom. Arrange your stuffed shells in the dish, then pour the remaining marinara sauce over them. Sprinkle the remaining mozzarella and Parmesan cheese on top.

Cover the dish with foil and bake for 25 minutes.

After 25 minutes, remove the foil and bake for another 10 minutes, or until the cheese is bubbly and golden brown.

Garnish with fresh basil before serving. Enjoy your comforting meal!