Preheat oven to 375°F (190°C) and grease a baking dish.
Cook pasta shells until al dente according to package instructions. Drain and set aside.
In a skillet, brown the ground beef over medium heat. Drain excess fat and stir in marinara sauce. Set aside.
In a bowl, mix ricotta cheese, egg, Italian seasoning, salt, and pepper until smooth.
Fill each pasta shell with the ricotta mixture and place into the prepared baking dish.
Pour the beef and marinara mixture over the stuffed shells evenly.
Sprinkle mozzarella and Parmesan cheese over the top.
Cover with foil and bake for 25 minutes. Remove foil and bake an additional 10 minutes until bubbly and golden.
Let cool slightly before serving. Enjoy!
