Step 1: Marinate the Chicken : In a large bowl, whisk together buttermilk, hot sauce, garlic powder, onion powder, paprika, salt, and pepper. Add the chicken pieces and coat well. Cover and refrigerate for at least 4 hours or overnight for maximum tenderness and flavor.
Step 2: Prepare the Dredging Mix : In another bowl, combine flour, cornstarch, paprika, cayenne, salt, and pepper. Remove chicken from the marinade, letting excess drip off. Dredge each piece in the flour mixture, pressing firmly to coat evenly. Let the coated chicken rest for 10 minutes before frying to help the coating stick.
Step 3: Fry the Chicken : Heat oil in a heavy-bottomed skillet or Dutch oven to 350°F (175°C). Carefully lower each chicken piece into the hot oil. Fry for 6–7 minutes per side or until golden brown and cooked through (internal temp 165°F / 74°C). Transfer to a wire rack to drain excess oil.
Step 4: Make the Nashville Hot Oil : Carefully ladle about ½ cup of the hot frying oil into a heatproof bowl. Whisk in cayenne, brown sugar, paprika, garlic powder, chili powder, and salt until smooth. Brush or spoon this hot mixture generously over the fried chicken.
Step 5: Assemble the Sandwiches : Toast brioche buns with butter until golden. Place the hot chicken on the bottom bun. Top with dill pickles and (optional) creamy coleslaw or lettuce. Add the top bun and serve immediately!