Cook the Shells: Bring a large pot of salted water to a boil. Cook the pasta shells according to package directions until al dente. Drain and rinse with cool water. Set aside.

Make the Filling: In a large mixing bowl, combine shredded chicken, ricotta, mozzarella, Parmesan, egg, garlic powder, Italian seasoning, salt, and pepper. Mix until well combined.

Stuff the Shells: Preheat the oven to 350°F (175°C). Spread 1 cup of Alfredo sauce on the bottom of a greased 9×13-inch baking dish. Carefully stuff each cooked shell with about 2 tablespoons of the chicken mixture and place in the dish.

Add the Sauce & Cheese: Pour the remaining Alfredo sauce evenly over the stuffed shells. Sprinkle extra mozzarella cheese on top for a melty finish.

Bake: Cover with foil and bake for 25 minutes. Remove foil and bake for another 10 minutes, until bubbly and golden.

Serve: Garnish with chopped parsley if desired and serve hot with a side salad or garlic bread.