Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish.

Cook the penne pasta according to package directions until al dente. Drain well and set aside.

In a large saucepan or Dutch oven, melt the butter over medium heat. Add the minced garlic and cook until fragrant, about 30 seconds.

Whisk in the flour and cook for 1 minute, stirring constantly, to form a roux.

Gradually pour in the milk, whisking continuously to ensure the sauce is smooth. Bring the sauce to a simmer and cook for 5-7 minutes, until it has thickened.

Reduce the heat to low and stir in the cubed cream cheese until it has fully melted. Add the salt, pepper, Italian seasoning, onion powder, and half of the Parmesan cheese. Stir until everything is combined and the sauce is velvety smooth.

Add the cooked pasta and shredded chicken to the sauce. Stir gently until everything is well-coated.

Pour the mixture into the prepared baking dish and spread evenly.

Sprinkle the shredded mozzarella and the remaining Parmesan cheese over the top.

Bake for 20-25 minutes, or until the cheese is melted and bubbly and the edges are golden brown. For a crispier top, you can broil for the last 1-2 minutes.

Let the pasta bake rest for 5-10 minutes before serving. Garnish with fresh parsley if desired.