Marinate: In a large bowl, whisk together buttermilk, hot sauce, salt, paprika, pepper, garlic powder, and onion powder. Submerge chicken pieces, cover, and refrigerate for 6–24 hours.
Prepare Dredge: In a shallow dish, combine flour, cornstarch, paprika, cayenne, baking powder, garlic powder, onion powder, thyme, salt, and pepper. Whisk until uniform.
Dredge Chicken: Remove chicken from marinade, letting excess drip off. Coat each piece in the flour mixture. For extra crunch, dip back into buttermilk and dredge a second time.
Heat Oil: In a heavy‑bottomed pot or Dutch oven, heat oil to 325–350 °F (165–175 °C). Use a thermometer for accuracy.
Fry in Batches: Carefully lower 3–4 pieces into the hot oil. Fry dark meat 12–14 minutes, white meat 10–12 minutes, turning once halfway. Avoid overcrowding.
Drain & Rest: Transfer to a wire rack over a baking sheet. Rest 10 minutes before serving to let juices redistribute.