Place the chicken drumsticks with the skin on in a plastic bag and pour the buttermilk into the bag. Squeeze the air out and seal the bag. Let marinate in the refrigerator for 30 minutes minimum up to several hours.
In a shallow bowl combine the panko breadcrumbs, flour, baking powder, and spices.
Preheat AirFryer to 390°F (200°C) (or don't preheat it and just fry the chicken 2 minutes longer).
Remove the chicken from the buttermilk, shake off excess buttermilk, and dredge the drumsticks in the seasoned flour mixture to coat on all sides.
Put the chicken in one layer in the Air Fryer basket and air fry for 10 minutes.
Then pause the AirFryer and brush drumsticks with melted butter on both sides. Turn the chicken over, lower the temperature to 350°F (180°C) and air fry for 7-10 more minutes or until internal temperature reads 165°F (79°C). Depending on the Air Fryer you use this time can be longer or shorter. Always make sure chicken is completely cooked through.
Remove from Airfryer and let the drumsticks rest for 5 minutes before serving.