01 - Combine buttermilk and hot sauce in a large bowl. Add chicken pieces and turn to coat thoroughly. Cover and refrigerate for at least 1 hour, or overnight for maximum tenderness.
02 - Preheat oven to 450°F. Whisk together flour, baking powder, baking soda, salt, and sugar in a large bowl. Cut in cold butter until mixture resembles coarse crumbs. Stir in buttermilk just until dough comes together.
03 - Turn dough onto a floured surface and gently pat to 1-inch thickness. Cut out biscuits using a 2.5-inch cutter. Place on a parchment-lined baking sheet and bake for 12–15 minutes until golden brown. Cool slightly.
04 - Mix flour, salt, pepper, paprika, garlic powder, onion powder, and cayenne in a shallow dish. Remove chicken from marinade, allowing excess to drip off. Dredge in flour mixture, pressing firmly to adhere.
05 - Heat 1 inch of oil to 350°F in a large, deep skillet or Dutch oven. Fry chicken in batches, turning occasionally, until golden brown and cooked through to internal temperature of 165°F, about 12–15 minutes per batch. Drain on a wire rack.
06 - Melt butter over medium heat in a saucepan. Whisk in flour and cook for 1–2 minutes. Gradually whisk in milk until smooth. Cook, stirring constantly, until thickened, 4–5 minutes. Season with salt, pepper, and garlic powder.
07 - Arrange fried chicken and biscuits on plates. Spoon warm gravy over biscuits and serve immediately.