01 - Whisk buttermilk with salt, garlic powder, onion powder, cayenne, and black pepper in a large bowl until fully combined. Add chicken pieces, turning to coat completely. Cover bowl and refrigerate for at least 2 hours or preferably overnight for maximum flavor penetration.
02 - Combine flour, paprika, salt, black pepper, cayenne, and baking powder in a separate bowl. Whisk thoroughly to distribute spices evenly throughout the flour mixture.
03 - Remove chicken from marinade, allowing excess liquid to drip off. Press each piece firmly into the flour mixture, ensuring complete coverage on all sides. Place coated pieces on a wire rack and let rest for 10 minutes to help coating adhere.
04 - Pour vegetable oil into deep fryer or large heavy pot to depth of at least 3 inches. Heat oil to 350°F, monitoring temperature with kitchen thermometer for accuracy.
05 - Carefully lower chicken pieces into hot oil using tongs, working in batches to avoid overcrowding. Fry for 12-15 minutes, turning occasionally, until exterior is deep golden brown and crispy, and internal temperature reaches 165°F.
06 - Transfer fried chicken to wire rack or paper towels to drain excess oil. Let rest for 5 minutes before serving to allow juices to redistribute and coating to set.