In a skillet melt butter over medium heat. Stir in hot sauce until combined.
Stir in shredded chicken until meat is fully coated with hot sauce. Continue to cook until heated through. Set aside.
Turn on broiler.
Slice each ciabatta roll in half and toast.
Spread 2 tablespoons of the blue cheese yogurt dressing on the bottom halves of ciabatta bread. Next divide the onions, tomato slices and shredded chicken evenly on top of the dressing. Make sure to put the onions and tomatoes under the chicken. This warms them up nicely but still gives a nice crunch.
Top each sandwich with ½ slice of provolone cheese.
Broil for 3-5 minutes or until cheese is melted. Keep an eye on it because the cheese can go from melted to burn very quickly.
Top with other half of the bread and serve.