In a medium bowl, combine the buttermilk, garlic powder, onion powder, paprika, salt, and black pepper
Cut the chicken breasts into desired pieces and place them in a zip-top bag or shallow dish. Pour the marinade over the chicken, ensuring it is fully coated. Seal the bag or cover the dish and refrigerate for at least 1 hour, or up to 24 hours for best results.
In a shallow bowl, mix together the flour and cornstarch.
Remove the chicken pieces from the marinade, allowing any excess to drip off. Dredge each piece in the flour-cornstarch mixture, pressing lightly to ensure an even coating. Shake off any excess.
Preheat your air fryer to 375°F (190°C) for about 5 minutes.
Lightly spray the air fryer basket with cooking spray. Place the coated chicken pieces in the basket in a single layer, ensuring they do not overlap. Lightly spray the tops of the chicken with cooking spray.
Air fry the chicken at 375°F (190°C) for 10-12 minutes, flipping halfway through, until the chicken is golden brown and crispy and has an internal temperature of 165°F (74°C).
Let the chicken rest for a few minutes before serving. Enjoy your crispy, delicious air fryer buttermilk fried chicken!