01 - Combine buttermilk and hot sauce in a large bowl. Submerge chicken pieces completely, cover bowl, and refrigerate for minimum 30 minutes up to 8 hours for optimal tenderness.
02 - Mix flour, paprika, garlic powder, onion powder, salt, black pepper, and cayenne in a separate bowl until thoroughly combined.
03 - Remove chicken from marinade, allowing excess liquid to drip off. Press each piece firmly into seasoned flour mixture, ensuring complete coverage. Transfer coated pieces to wire rack.
04 - Heat 1 inch vegetable oil in 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.
06 - Whisk flour, baking powder, baking soda, salt, and sugar together. Cut in cold butter using pastry blender or fingers until mixture resembles coarse crumbs. Stir in buttermilk until dough just comes together.
07 - Turn dough onto floured surface and pat to 1-inch thickness. Cut rounds with biscuit cutter. Place on baking sheet, brush tops with buttermilk, and bake 12 to 15 minutes until golden brown.
08 - Melt butter in saucepan over medium heat. Whisk in flour and cook for 2 minutes. Gradually whisk in milk, stirring constantly until thickened, 5 to 7 minutes. Season with black pepper and salt.
09 - Plate fried chicken alongside warm biscuits. Ladle generous amount of peppered gravy over chicken and serve immediately.