01 - Combine buttermilk, hot sauce, salt, and black pepper in a large mixing bowl. Add chicken thighs, ensuring full submersion. Refrigerate for at least 20 minutes, or up to 12 hours.
02 - In a shallow dish, mix all-purpose flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt until thoroughly blended.
03 - Remove chicken thighs from marinade, allowing excess liquid to drain. Dredge each piece in the seasoned flour mixture, pressing firmly to coat. Rest on a wire rack for 10 minutes.
04 - Pour vegetable oil into a heavy skillet or Dutch oven to a depth of 1 inch. Heat oil to 350°F (175°C).
05 - Using tongs, fry chicken thighs in batches for 5 to 7 minutes per side until golden brown, crispy, and internal temperature reaches 165°F (74°C). Transfer to a clean wire rack.
06 - In a medium bowl, whisk together 0.5 cup of hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt until smooth. Generously brush both sides of fried chicken.
07 - If desired, spread unsalted butter on cut sides of brioche buns and toast in a skillet until golden brown.
08 - Place sauced chicken thigh on each bun's bottom half. Top with dill pickle chips and a generous portion of coleslaw. Cap with the top bun and serve hot.