Preheat your oven to 350°F (175°C).

In a large skillet, cook the ground beef over medium heat for 6-8 minutes until browned.

In a large mixing bowl, combine the cooked ground beef with ricotta, mozzarella, egg, Italian seasoning, garlic powder, salt, and black pepper.

Bring a large pot of salted water to a boil and cook the pasta shells for about 8-10 minutes until al dente. Drain and rinse with cold water.

Carefully fill each pasta shell with the filling and place in a greased baking dish.

Pour the marinara sauce over the shells and sprinkle grated Parmesan cheese on top.

Cover the baking dish with aluminum foil and bake for 30-35 minutes. Remove the foil and bake for an additional 5-10 minutes until golden.

Garnish with fresh basil or parsley before serving.