Preheat oven to 350°. In a large skillet, cook chicken over medium heat until no longer pink, 5-7 minutes, breaking into crumbles; drain. Transfer chicken to a large bowl; stir in sour cream, 1 cup cheddar cheese, 1 cup blue cheese, wing sauce, butter and pepper., Transfer chicken mixture to a greased 8-in. square baking dish. Top with remaining cheeses and crushed chips. Bake until cheese is melted, 10-12 minutes. Top with green onions and bacon. Serve with celery sticks and chips.