Dry overnight if possible: lay wings on a wire rack over a rimmed baking tray and refrigerate uncovered. If short on time, pat wings very dry with paper towels.

Preheat oven to 250 F / 120 C. Position one shelf in the lower quarter and one in the upper quarter of the oven.

Line the baking tray with foil, place the wire rack on top, and spray the rack generously with cooking oil.

Place wings in a large bowl. Sprinkle baking powder and salt over the wings and toss very thoroughly with your hands or shake in a ziplock bag until every surface is evenly coated.

Arrange wings skin side up on the rack. They can sit snugly as they will shrink during baking. Bake on the lower shelf for 30 minutes at 250 F.

Move the tray to the upper shelf and increase oven temperature to 425 F / 220 C. Bake for 40 to 50 minutes, rotating the tray once halfway through. Do not flip the wings. They are ready when deep golden brown and the skin is very crispy.

Whisk together melted butter, Frank's hot sauce, brown sugar, and salt in a small saucepan over low heat until the sugar fully dissolves. Keep warm until ready to use.

Mash softened blue cheese into sour cream until mostly smooth or slightly lumpy to your preference. Stir in minced garlic, mayonnaise, lemon juice, salt, and pepper. Add milk one tablespoon at a time to reach desired consistency. Refrigerate until needed and remove from the fridge 15 minutes before serving.

Transfer hot wings to a large bowl. Pour the warm buffalo sauce over and toss to coat every wing. Serve immediately with blue cheese dip and celery sticks.