Preheat oven to 400°F (200°C). Line a large rimmed baking sheet with parchment paper or foil.
In a medium bowl, combine shredded chicken, buffalo sauce, and melted butter. Toss to coat evenly.
Spread tortilla chips in an even layer on the prepared baking sheet. Top with half the cheese, then the buffalo chicken mixture, then remaining cheese.
Bake for 10-12 minutes until cheese is melted and bubbly.
Remove from oven and immediately sprinkle with blue cheese (if using), tomatoes, green onions, and cilantro.
Drizzle with sour cream and ranch/blue cheese dressing. Serve immediately.
Tips
Adjust spice level by using mild or extra-hot buffalo sauce.
For extra crunch, add a layer of pickled jalapeños before baking.
Leftovers can be reheated in a 350°F oven for 5 minutes, but nachos are best fresh.