Slice the chicken breast into cutlets or pound to an even thickness for quicker, uniform cooking.
In a shallow bowl, pour the buttermilk and add a pinch of salt and pepper. Submerge the chicken pieces in the buttermilk, ensuring they're fully coated. Let marinate in the refrigerator for at least 30 minutes.
In a separate bowl, combine the whole wheat flour, panko breadcrumbs, garlic powder, paprika, black pepper, and remaining salt. Mix well.
Remove the chicken from the buttermilk, allowing excess to drip off. Dredge each piece thoroughly in the flour-panko mixture, pressing gently to ensure the coating sticks.
Preheat your air fryer to 400°F for about 3-5 minutes. Lightly spray the air fryer basket with cooking spray.
Place the coated chicken pieces in the air fryer basket in a single layer, ensuring they do not overlap. Lightly spray the top of the chicken with cooking spray.
Air-fry the chicken for 10 minutes, then flip and cook for another 5-7 minutes until the coating is golden brown and the chicken is cooked through.
Remove from the air fryer, let rest for a couple of minutes, and serve immediately.