Preheat your oven to 350°F (175°C).

Bring a large pot of salted water to a boil. Add the jumbo pasta shells and cook for 8-10 minutes or until al dente. Drain and set aside.

In a skillet over medium heat, brown the ground beef until fully cooked. Drain excess grease.

In a bowl, combine ricotta cheese, half of the mozzarella cheese, Parmesan cheese, egg, Italian seasoning, garlic powder, salt, and pepper. Once the beef is cooled, mix it into the cheese mixture until well combined.

Using a spoon, fill each cooked shell with the beef and cheese mixture.

Spread half of the marinara sauce on the bottom of a baking dish. Place the stuffed shells in the dish, seam side up, and cover with the remaining marinara sauce.

Sprinkle the remaining mozzarella over the top of the shells.

Cover the dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes or until the cheese is bubbly and slightly golden.

Let it cool for a few minutes, garnish with fresh basil if desired, and then serve!