Combine Frank's hot sauce, butter, vinegar, cayenne, garlic powder, celery salt and Worcestershire sauce in a medium-size pot. Turn the heat to medium and let the mixture simmer for 10 to 20 minutes or until the sauce is smooth. Season with salt to taste and remove from heat when the desired consistency is reached. Reserve about 2 tablespoons for this recipe and store the remaining sauce in an airtight container in the refrigerator.

Toss the chopped chicken fingers with Buffalo sauce and set aside. Place half the cheddar on 1 slice of bread and add the Buffalo sauce–doused chicken. Drizzle ranch dressing on top and add blue cheese and chives. Add the rest of the cheddar and place the remaining piece of bread on top. Butter the exterior of the sandwich.

Place the buttered sandwich in a medium-size cast-iron skillet or panini press and turn the heat to medium. Let the sandwich cook on each side, flipping if necessary, until the bread has crisped up and all the cheese has melted; about 5 to 7 minutes. Once the sandwich is done cooking, remove it from heat, let it sit for 1 minute, then slice. Serve immediately with an extra side of Buffalo sauce for dipping.