Bring a large pot of salted water to a boil. Cook the jumbo pasta shells according to package instructions until al dente, usually about 10-12 minutes. Drain and set aside to cool slightly.
In a large mixing bowl, combine the shredded chicken, ricotta cheese, half of the mozzarella, half of the Parmesan cheese, garlic powder, salt, and pepper. Mix until well combined.
Carefully fill each cooked pasta shell with the chicken and cheese mixture. Place the stuffed shells in a greased baking dish.
Pour the Alfredo sauce evenly over the stuffed shells, ensuring they are well-coated.
Sprinkle the remaining mozzarella and Parmesan cheese on top of the shells for a cheesy finish.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Remove from the oven and let it cool for a few minutes. Garnish with fresh parsley before serving.
Notes
Feel free to use store-bought Alfredo sauce for convenience.