Preheat the oven to 375°F.
Bring a large pot of salted water to a boil.
Cook the pasta until just al dente, about 1–2 minutes less than the package instructions.
Drain the pasta and set it aside.
In a large mixing bowl, combine the shredded chicken, buffalo sauce, ranch or blue cheese dressing, garlic powder, onion powder, ¾ cup of the shredded cheddar cheese, and a pinch of salt and pepper.
Stir until everything is fully combined.
Add the cooked pasta to the bowl and mix until evenly coated.
Transfer the mixture to a greased 9x13-inch baking dish.
Top with the remaining ¾ cup shredded cheddar cheese and the ½ cup shredded mozzarella cheese.
Bake uncovered for 20–25 minutes, or until the top is bubbly and lightly golden.
Remove from the oven and let it rest for 5 minutes.
Garnish with chopped green onions or parsley, if desired.
Serve warm.