Preheat your oven to 350°F (175°C). Assemble your ingredients while the oven is heating.

Cook the manicotti shells according to the package instructions for about 8-10 minutes, then drain and cool slightly.

In a skillet, heat a splash of oil over medium heat. Cook diced chicken until no longer pink, about 5-7 minutes, and season with salt and pepper.

In a mixing bowl, combine the cooked chicken, ricotta cheese, mozzarella, Parmesan, salt, pepper, and garlic powder. Stir until well incorporated.

Fill each manicotti shell with the chicken-cheese mixture using a spoon or piping bag.

In a saucepan, melt butter and sauté minced garlic for 1 minute. Pour in heavy cream, simmer for 3-4 minutes, then stir in remaining Parmesan until thickened.

Spread a thin layer of Alfredo sauce in a baking dish, arrange filled shells in a single layer, and pour remaining sauce over the shells.

Cover with foil and bake for 30 minutes. Remove foil and bake for an additional 10-15 minutes until golden and bubbly.

Let sit for a few minutes, then garnish with parsley and serve warm.