Marinate the Chicken: In a large bowl, combine buttermilk, hot sauce, salt, and pepper. Add chicken pieces, coat well, cover, and refrigerate for at least 4 hours (overnight for best flavor).
Prepare Coating: In a separate bowl, whisk together flour, baking powder, paprika, garlic powder, onion powder, cayenne, salt, and pepper.
Dredge Chicken: Remove chicken from buttermilk, letting excess drip off. Dredge each piece in flour mixture, pressing firmly to coat. Place on a wire rack and let rest for 10–15 minutes.
Fry Chicken: Heat 2–3 inches of oil in a deep skillet or Dutch oven to 350°F (175°C). Fry chicken in batches for 12–15 minutes, turning halfway, until golden brown and internal temperature reaches 165°F (74°C).
Drain: Place on a wire rack or paper towel–lined tray to drain excess oil.