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 - In a separate large bowl, whisk together flour, paprika, garlic powder, onion powder, salt, black pepper, and cayenne until thoroughly blended.
03 - Remove chicken from marinade, allowing excess liquid to drip off. Press each piece firmly into the seasoned flour mixture, ensuring complete coverage. Shake gently to remove excess coating and arrange on a wire rack.
04 - Heat 1 inch of vegetable oil in a heavy skillet or Dutch oven to 350°F. Fry chicken in batches without overcrowding, cooking 8-12 minutes per side until golden brown and internal temperature reaches 165°F. Transfer to paper towels to drain.
05 - Preheat oven to 425°F and prepare a baking sheet with parchment paper or light greasing.
06 - Whisk flour, baking powder, baking soda, salt, and sugar in a large bowl. Cut in cold butter using a pastry cutter or fingers until mixture resembles coarse crumbs with some pea-sized butter pieces remaining. Pour in cold buttermilk and stir gently just until dough comes together.
07 - Turn dough onto a floured surface and pat gently to 1-inch thickness. Cut rounds using a biscuit cutter or glass, pressing straight down without twisting. Place on prepared baking sheet, brush tops with buttermilk, and bake 12-15 minutes until golden brown.
08 - Melt butter in a saucepan over medium heat. Whisk in flour and cook for 2 minutes, stirring constantly to form a roux. Gradually pour in milk while whisking continuously to prevent lumps. Simmer 5-7 minutes until thickened. Season with black pepper and salt.
09 - Place warm biscuits on serving plates, arrange fried chicken alongside, and ladle generous amounts of peppered gravy over the chicken and biscuits. Serve immediately while hot.