1 tablespoon blue cheese, room temperature, crumbled
1/2 cup cheddar cheese, room temperature, grated
2 slices bread
1 tablespoon butter, room temperature
Mix the chicken, hot sauce, mayo, carrot, celery and onion in a small bowl.
Butter the outside of each slice of bread, sprinkle half of the cheeses on the inside of one slice of bread, top with the buffalo chicken salad, the remaining cheese and finally the other slice of bread.
Heat a non-stick pan over medium heat.
Add the sandwich and grill until golden brown and the cheese has melted, about 2-4 minutes per side.