Preheat oven to 350°F (175°C).
Cook manicotti shells according to package instructions. Drain and set aside.
In a mixing bowl, combine ricotta, half of the mozzarella, Parmesan, egg, salt, pepper, and basil.
Stuff each manicotti shell with the cheese mixture.
Spread 1 cup of marinara sauce on the bottom of a baking dish.
Place stuffed shells in the baking dish and cover with remaining marinara sauce.
Sprinkle remaining mozzarella cheese on top.
Bake for 30-35 minutes, until bubbly and golden.
Let cool for a few minutes before serving.