In bowl, combine butter and 1 tbsp. hot sauce. In another bowl, mix chicken, salt, pepper and 1/4 cup hot sauce butter. Form into 8 meatballs. In medium nonstick skillet, heat oil over medium. Add meatballs; cook until browned all over and cooked through, about 10 minutes. Off heat, douse meatballs with hot sauce. Top each with cheese. Cover skillet until cheese melts. Dip bun bottoms, toasted side down, into remaining hot sauce butter. Build sliders with buns, celery and meatballs.