Prepare the Pasta:

1. Cook the Pasta: Bring a large pot of salted water to a boil. Cook the jumbo pasta shells according to the package directions until al dente. Drain and set aside to cool slightly.

Make the Beef Filling:

2. Cook the Ground Beef: In a large skillet, heat a tablespoon of olive oil over medium heat. Add the ground beef, onion, and garlic, and cook until the beef is browned, breaking it up with a spoon as it cooks. Drain excess fat if necessary.
3. Season the Beef: Stir in the dried basil, oregano, salt, and pepper, then remove from heat and set aside to cool slightly.
4. Mix the Filling: In a mixing bowl, combine the cooked beef mixture, ricotta cheese, 1 cup of shredded mozzarella, and the egg. Stir until well combined.

Assemble the Stuffed Shells:

5. Preheat the Oven: Preheat your oven to 375°F (190°C).
6. Stuff the Shells: Take each cooked pasta shell and carefully stuff it with the beef and cheese mixture. Arrange the stuffed shells in a 9×13-inch baking dish, placing them seam side down.

Bake the Stuffed Shells:

7. Top with Sauce and Cheese: Pour the marinara sauce over the stuffed shells, ensuring they are all covered. Sprinkle the remaining ½ cup of mozzarella cheese evenly over the top.
8. Bake: Cover the baking dish with aluminum foil and bake for 25 minutes. Then, remove the foil and bake for an additional 10-15 minutes, until the cheese is melted and bubbly and the shells are heated through.

Garnish and Serve:

9. Garnish and Serve: Remove from the oven and sprinkle with fresh chopped parsley. Serve hot, with extra marinara sauce on the side if desired.