Preheat oven to 350 F degrees, on a baking sheet place chicken thighs. Season with garlic powder, salt & pepper. Bake until juices run clear, turning once, about 30 mins.
On a large pizza pan or baking sheet place a single layer (slightly overlapping) of chips. Sprinkle about a 1/3 of the cheese on the chips. In a medium bowl mix buffalo sauce and chicken until evenly coated. Then layer chicken on top of cheese and chips. Sprinkle with remaining cheese and bake until cheese is melted. Remove from oven and top with celery and dressing.