01 - In a large bowl, whisk together the buttermilk, salt, garlic powder, onion powder, cayenne pepper, and black pepper until thoroughly combined. Add the chicken pieces and turn to coat completely. Cover the bowl and refrigerate for at least 2 hours, preferably overnight for maximum flavor penetration.
02 - In a separate large bowl, combine the flour, paprika, salt, black pepper, cayenne pepper, and baking powder. Whisk until evenly distributed to ensure consistent seasoning on each piece.
03 - Remove the chicken from the marinade, allowing excess liquid to drip off. Dredge each piece in the flour mixture, pressing firmly to adhere a thick, even coating. Shake off any excess flour, then place the coated pieces on a wire rack and let rest for 10 minutes to set the coating.
04 - Pour vegetable oil into a deep fryer or large heavy-bottomed pot to a depth of at least 3 inches. Heat the oil to 350°F, using a kitchen thermometer to verify the temperature.
05 - Carefully lower the chicken pieces into the hot oil in small batches, being careful not to overcrowd the pot. Fry for 12 to 15 minutes, turning occasionally, until the coating is golden brown and crispy and the internal temperature reaches 165°F when measured with a meat thermometer.
06 - Transfer the fried chicken to a wire rack or paper towels to drain excess oil. Let rest for 5 minutes before serving to allow the juices to redistribute.