Preheat oven to 450F.
Place a large skillet over medium-high heat with 2 turns of the pan of EVOO, about 2 tablespoons. Season the chicken pieces with salt and ground black pepper, and add them to the preheated skillet. Saut until cooked through and golden brown, 4-5 minutes.
Reduce the heat to medium and add the butter to the skillet to melt. Add the hot sauce and cook, stirring occasionally, until the sauce has thickened and coats the chicken, 2-3 minutes. (Be careful not to take a deep breath over the pan or the hot sauce fumes could burn your sinuses!)
When the chicken is ready, place the flatbread rounds on a baking sheet and divide the chicken equally between all four rounds. Scatter the celery over the chicken and top each round with some shredded cheese and blue cheese crumbles. Bake until the bread is crisped and the cheese has melted, about 5 minutes.