01 - In a large mixing bowl, whisk buttermilk, hot sauce, salt, and ground black pepper. Submerge chicken thighs and marinate for at least 20 minutes or refrigerate up to overnight.
02 - In a shallow dish, thoroughly combine flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt.
03 - Remove chicken from marinade, allowing excess to drip off. Dredge each piece in the flour mixture, pressing firmly to ensure even coating. Arrange coated chicken on a wire rack and let rest for 10 minutes.
04 - Pour vegetable oil into a large heavy skillet to a depth of 1 inch. Heat oil to 350°F. Maintain a steady temperature for optimal frying.
05 - Fry chicken thighs in batches for 5–7 minutes per side until golden brown, crispy, and internal temperature reaches 165°F. Transfer cooked chicken to a wire rack.
06 - In a medium bowl, carefully combine 1/2 cup of the hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt. Whisk until fully blended, then brush generously over both sides of the fried chicken.
07 - If desired, spread butter on the cut sides of brioche buns and toast in a skillet until golden and crisp.
08 - Arrange a piece of sauced chicken on each bun bottom. Layer with dill pickle chips and a generous scoop of coleslaw. Cover with the top bun and serve immediately.