Preheat your oven to 350°F (175°C).
Cook the manicotti shells according to the package instructions. Drain and set aside.
In a mixing bowl, combine ricotta cheese, ½ cup mozzarella cheese, ¼ cup Parmesan cheese, egg, salt, and pepper. Mix well.
Fill each manicotti shell with the cheese mixture.
Spread 1 cup of marinara sauce on the bottom of a baking dish.
Place the filled shells in the baking dish and cover with the remaining marinara sauce.
Sprinkle the remaining mozzarella and Parmesan cheese on top.
Bake for 30-35 minutes, or until the cheese is bubbly and golden.
Garnish with fresh basil before serving.