Preheat the oven to 375°F (190°C). Cook the pasta according to package instructions until al dente. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sauté for 1 minute until fragrant.
Add the butter to the skillet. Once melted, whisk in the flour to form a roux. Cook for 1-2 minutes.
Gradually whisk in the milk and heavy cream until smooth. Bring to a simmer and cook until the sauce thickens, about 5 minutes.
Stir in the Parmesan cheese, Italian seasoning, salt, black pepper, and red pepper flakes (if using). Mix until the cheese is melted and the sauce is smooth.
Add the cooked pasta and chicken to the sauce, stirring to coat evenly.
Transfer the mixture to a baking dish. Sprinkle the mozzarella cheese evenly over the top.
Bake for 20-25 minutes, until the cheese is bubbly and golden. Garnish with chopped parsley before serving.
Notes
For extra flavor, you can add sautéed mushrooms or spinach to the dish before baking.