Marinate the chicken. In a large bowl, whisk buttermilk, hot sauce (if using), 2 teaspoons salt, and 1/2 teaspoon black pepper. Add chicken and toss to coat. Cover and refrigerate for at least 4 hours, ideally overnight for best tenderness.

Set up the coating. In a shallow dish, mix flour, cornstarch, paprika, garlic powder, onion powder, cayenne, baking powder, and the remaining salt and pepper. Stir well to distribute the spices evenly.

Preheat the air fryer. Set to 375°F (190°C) for 5 minutes. A hot basket jump-starts crisping.

Coat the chicken. Shake excess buttermilk from each piece. Dredge in the flour mixture, pressing to form a clinging coat. For extra crunch, dip back in buttermilk and dredge a second time. Place coated pieces on a rack for 5 minutes to help the crust set.

Oil the surfaces. Lightly spray both sides of the chicken with oil. Do not soak it. A thin, even layer helps browning without sogginess.

Arrange in the basket. Place chicken in a single layer with space between pieces. Work in batches to avoid crowding, which prevents crisping.

Air fry and flip. Cook at 375°F (190°C) for 22–28 minutes, flipping halfway and spraying any dry patches. Thighs and drumsticks usually take 24–26 minutes; large bone-in breasts may need up to 30 minutes. Aim for 165°F (74°C) internal temperature at the thickest point.

Rest before serving. Let chicken rest on a wire rack for 5–7 minutes. This keeps the crust crisp and the juices in the meat.

Finish and serve. Sprinkle with a pinch of salt, a squeeze of lemon, and chopped herbs if you like. Serve hot with slaw, pickles, or cornbread.