Preheat the oven to 250ºF and place a baking rack above a large baking sheet. Lightly grease the rack.
Place half of the wings in a heavy duty ziploc back and sprinkle with half of the baking powder. Shake vigorously to coat, then place the wings on the prepared rack. Repeat with the remaining wings and the remaining baking powder.
Bake 30 minutes, until the wings feel dry and crisp to the touch. Remove the wings and increase the heat to 425ºF.
Transfer the wings to a large mixing bowl. Toss with the melted butter and about three quarters of the Cajun seasoning. Place back on the rack, skin side down. Bake 15 minutes.
Flip the wings over so they are skin-side up and sprinkle with the remaining Cajun seasoning. Bake another 10 minutes, then turn off the oven and let them stay inside until crisp to your liking.
Notes
Storage Information: Store the wings in a covered container in the fridge for up to 5 days. Re-warm them in the oven to help make them crispy again.