Preheat your oven to 350°F (175°C).
Cook the penne pasta according to the package directions until al dente. Drain, rinse lightly, and set aside.
In a medium saucepan over medium heat, melt the butter with the heavy cream and cream cheese.
Whisk until smooth and fully combined.
Stir in the minced garlic, garlic powder, Italian seasoning, salt, and black pepper.
Add the grated Parmesan cheese and continue whisking until melted.
Simmer the sauce for 3–5 minutes until slightly thickened.
Combine the cooked pasta, chopped chicken, and Alfredo sauce until evenly coated. This creates the perfect Baked Chicken Alfredo Pasta filling.
Spread half of the pasta mixture into a greased 9×13-inch baking dish.
Sprinkle with half of the mozzarella cheese.
Add the remaining pasta mixture.
Top with the remaining mozzarella and the extra Parmesan cheese.
Bake for 20–30 minutes until hot, bubbly, and lightly golden.
Let the casserole rest for 5 minutes before serving.