Bring a large pot of salted water to a boil. Add 8 ounces of penne pasta and cook according to package instructions until al dente, about 10-12 minutes. Drain the pasta in a colander and set aside.
In a large mixing bowl, add 2 cups of cooked, shredded roasted chicken. Pour in 2 cups of Alfredo sauce, then sprinkle 1 teaspoon garlic powder, 1/2 teaspoon Italian seasoning, salt, and pepper to taste. Stir everything until the chicken is evenly coated in the sauce.
Add the drained penne pasta into the bowl with the chicken and Alfredo mixture. Gently toss to make sure every piece of pasta is coated with the creamy sauce and chicken.
Preheat your oven to 375°F (190°C). Lightly grease your baking dish. Transfer the pasta mixture into the dish and spread it evenly. Sprinkle 1 cup shredded mozzarella cheese on top, followed by 1/2 cup grated Parmesan cheese.
Place the dish in the preheated oven and bake for 20-25 minutes until the cheese on top is melted, bubbly, and lightly golden brown.
Remove from the oven and let it cool for 5 minutes. Sprinkle 1/4 cup chopped fresh parsley over the top for color and freshness. Serve warm and enjoy!