Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Cook pasta in salted water until just al dente. Drain and set aside.
Heat olive oil in a skillet over medium heat. Season shredded chicken with Italian seasoning, salt, and pepper. Cook for 2-3 minutes until warmed through. Set aside.
In the same skillet, melt butter over medium heat. Add minced garlic and cook until fragrant (about 1 minute).
Stir in flour and cook for 1-2 minutes to form a roux.
Slowly whisk in milk and chicken broth until smooth. Cook until the sauce thickens (about 5-7 minutes).
Stir in Parmesan cheese, Italian seasoning, and red pepper flakes. Season with salt and pepper.
In a large bowl, combine the cooked pasta, shredded chicken, and creamy garlic sauce. Mix well.
Pour the mixture into the prepared baking dish.
Sprinkle mozzarella and additional Parmesan cheese evenly on top.
Bake for 20-25 minutes or until bubbly and golden brown on top.
Garnish with freshly chopped parsley and serve warm.
