Preheat oven to 375°F and lightly grease a baking dish.
In a large bowl, mix the chicken with buffalo sauce until well coated.
Add Alfredo sauce and cooked penne pasta, then stir to combine.
Pour mixture into the prepared baking dish.
Top with mozzarella, cheddar, and Parmesan cheese.
Bake for 20–25 minutes until hot and bubbly.
Garnish with chopped parsley if desired and serve warm.