Bring a large pot of salted water to a boil and cook the pasta until al dente according to package instructions. Drain and set aside.
In a large skillet or saucepan over medium heat, combine the buffalo sauce, ranch or blue cheese dressing, cream cheese, and garlic powder. Stir until smooth and creamy.
Stir in the shredded chicken, then add the cooked pasta. Toss until everything is evenly coated in the buffalo cream sauce. Season with salt and pepper to taste.
Preheat your oven to 375°F (190°C). Transfer the buffalo chicken pasta mixture into a greased 9x13-inch baking dish. Top with shredded mozzarella and cheddar cheese.
Bake uncovered for 20–25 minutes, or until the cheese is melted and bubbly. Let it rest for 5 minutes before serving. Garnish with green onions, blue cheese crumbles, or a drizzle of buffalo sauce if desired.