For the blue cheese sauce: Combine the mayonnaise, blue cheese, sour cream, buttermilk, honey and garlic powder in a bowl and whisk until blended. Set aside.
For the buffalo chicken meatballs: Heat the olive oil in a medium saute pan over medium heat. Add the onion and saute until soft and translucent, 5 to 8 minutes. Let cool.
In large bowl, combine the buttermilk, torn bread and 2 tablespoons of the hot sauce and mix to form a paste. Add the ground chicken, breadcrumbs, ranch dressing mix, egg and 1/2 cup of the diced celery and mix with your hands until combined. Refrigerate for 30 minutes.
Preheat the oven to 450 degrees F. Line a baking sheet with aluminum foil and spray with cooking spray.
Form the meatball mixture into 16 even mini patties, about 2 1/2 inches in diameter. Place a cube of blue cheese in the center of a patty and wrap the meat around the cheese. Roll into a uniform ball and place on the prepared baking sheet. Continue with the remaining patties and cheese cubes, making sure to wash your hands in cold water a few times between rolling to keep the meatballs from sticking to your hands. Bake the meatballs until lightly browned, 15 to 20 minutes.
While the meatballs bake, prepare the buffalo sauce. In a medium pot over medium-low heat, combine the butter, honey and remaining 1 cup hot sauce. Heat until the butter is melted, whisking until well blended. Continue to cook until the sauce is heated through.
Transfer the meatballs to a large mixing bowl and pour over the buffalo sauce. Gently toss to coat and transfer to a platter. Garnish with a drizzle of the blue cheese sauce and the remaining 1/4 cup diced celery. Serve the rest of the blue cheese sauce on the side.