In a medium mixing bowl, whisk together the buttermilk, garlic powder, paprika, salt, and pepper. Pour into a gallon-sized food storage bag.
Add the chicken legs to the bag. Remove any air and seal the bag. Place in a dish in the fridge for at least 1 hour to overnight to marinate. (see note)
In a shallow bowl, stir together the flour, seasoned salt, garlic powder, onion powder, paprika, bails, oregano, and pepper. Coat the bottom of your air fryer basket really well with olive oil spray.
Dip 3-4 chicken legs into the breading until coated. Shake off any excess and then place them into your air fryer basket being sure the legs don't touch. (You may need to work in batches depending on the size of your air fryer.)
Cook at 390 degrees F for 12 minutes. Then use some tongs to flip the legs over. Place a 1/2 tablespoon pat of butter onto the meatiest part of each leg. Then cook for another 12 minutes at 390F.
Once the cooking time is up, check that the internal temp is at least 165 degrees F. When the chicken is done, remove it from the basket, blot with a paper towel, and place it on a wire rack. Repeat with the remaining ingredients. (see note)
Serve warm as it or with your favorite dipping sauce.
If you don't have buttermilk, you can make sour milk instead. Mix together 2 cups of milk + 2 tablespoons of lemon juice or distilled white vinegar. Stir together and let sit for 5 minutes before using.
You can leave the chicken legs in the marinade for up to 3 days in the fridge in an air-tight container.
I like to keep the cooked chicken legs warm by placing the wire rack over a baking sheet. Then I place the pan into a warm oven set to 200 degrees F until all the chicken is cooked.