01 - Combine buttermilk and hot sauce in a large bowl. Submerge chicken pieces completely, cover, and refrigerate for at least 30 minutes or up to 8 hours for maximum flavor penetration.
02 - Whisk together flour, paprika, garlic powder, onion powder, salt, black pepper, and cayenne in a shallow bowl until thoroughly combined.
03 - Remove chicken from buttermilk marinade, allowing excess liquid to drip off. Press each piece firmly into the seasoned flour mixture, ensuring complete coverage. Transfer coated pieces to a wire rack.
04 - Heat 1 inch of vegetable oil in a heavy skillet to 350°F. Fry chicken in batches without overcrowding, cooking 8 to 12 minutes per side until golden brown and internal temperature reaches 165°F. Drain on paper towels.
05 - Preheat oven to 425°F. Whisk flour, baking powder, baking soda, salt, and sugar in a bowl. Cut in cold butter using a pastry blender until mixture resembles coarse crumbs. Stir in buttermilk just until dough forms.
06 - Turn dough onto a floured surface and gently pat to 1-inch thickness. Cut rounds with a biscuit cutter. Place on a baking sheet, brush tops with buttermilk, and bake 12 to 15 minutes until golden brown.
07 - Melt butter in a saucepan over medium heat. Whisk in flour and cook for 2 minutes. Gradually pour in milk while whisking constantly. Simmer 5 to 7 minutes until thickened. Stir in black pepper and salt.
08 - Plate crispy fried chicken alongside warm buttermilk biscuits. Generously ladle hot peppered gravy over both chicken and biscuits.