Spread the tortilla chips in a thin layer onto the lined pan (half sheet size), using the whole surface area of the pan.
In a sauté pan, melt the butter over medium heat. Add the ground chicken and cook until no longer pink, breaking the meat up into small pieces as it cooks.
Drain the cooked chicken if necessary. Stir in two tablespoons of the red onion, a little salt and pepper and the buffalo sauce until the chicken is well coated with the sauce.
Layer the buffalo chicken mixture evenly on top of the nacho tortilla chips.
Layer the shredded cheese evenly on top of the buffalo chicken.
Bake the nachos in the preheated oven for 10 minutes, or until the cheese is hot and completely melted.
Remove the pan from the oven and immediately top the nachos. Drizzle the Ranch dressing over the top. And a little more buffalo wing sauce if desired.
Sprinkle them with the remaining red onion, chopped celery and cilantro.