Marinate the Chicken: In a bowl, mix buttermilk, salt, pepper, garlic powder, onion powder, and cayenne. Add chicken pieces, cover, and refrigerate for at least 2 hours (or overnight for best results).
Prepare the Coating: In another bowl, combine flour, cornstarch, baking powder, and optional spices. In a separate bowl, whisk eggs.
Bread the Chicken: Remove chicken from buttermilk and let excess drip off. Dip each piece in flour mixture, then into eggs, then back into the flour mixture. For extra crunch, coat in panko breadcrumbs. Let rest for 10 minutes.
Fry the Chicken: Heat vegetable oil in a deep skillet to 350°F (175°C). Fry chicken in batches for 6-8 minutes, until golden brown and cooked through. Drain on a wire rack.
Serve: Let chicken rest for a few minutes before serving. Pair with your favorite dipping sauces and sides