Cook the Pasta Shells:
Bring a large pot of salted water to a boil.
Add the jumbo pasta shells and cook for 8-10 minutes, until al dente.
Drain and rinse with cool water to stop the cooking process.
Prepare the Chicken Filling:
In a mixing bowl, combine 2 cups of shredded cooked chicken, 1 cup ricotta cheese, 1 cup shredded mozzarella, and ½ cup grated Parmesan cheese. Mix until smooth.
Season the Filling:
Add salt, pepper, and minced garlic to taste. For extra flavor, consider adding fresh herbs like parsley or basil.
Prepare the Alfredo Sauce:
In a saucepan, melt ½ cup butter over medium heat.
Stir in 1 cup heavy cream and allow it to simmer.
Add 1 cup Parmesan cheese, salt, pepper, and nutmeg, whisking until the cheese melts and the sauce becomes smooth.
Assemble the Dish:
Spread a thin layer of Alfredo sauce at the bottom of a 9×13 inch baking dish.
Stuff each cooled pasta shell with the chicken and cheese mixture.
Arrange the shells in the dish seam-side up.
Add Sauce and Cheese:
Pour the remaining Alfredo sauce over the stuffed shells.
Top with 1 cup shredded mozzarella and a sprinkle of grated Parmesan cheese.
Cover with aluminum foil and bake at 350°F (175°C) for 20 minutes.
Remove foil and bake for an additional 10 minutes to melt and brown the cheese
