01 - In a large bowl, combine buttermilk, hot sauce, salt, and black pepper. Submerge chicken thighs in the mixture and cover. Marinate for at least 20 minutes or up to overnight in the refrigerator.
02 - In a shallow dish, thoroughly mix all-purpose flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt.
03 - Remove chicken thighs from the marinade, letting excess liquid drip off. Dredge each thigh in the flour mixture, ensuring even coating by pressing firmly. Set coated chicken on a wire rack for 10 minutes to rest.
04 - Pour vegetable oil into a heavy skillet or Dutch oven to a depth of 1 inch. Heat oil to 350°F.
05 - Working in batches, fry the chicken thighs for 5 to 7 minutes per side until golden and internal temperature reaches 165°F. Transfer fried chicken to a wire rack to drain.
06 - In a medium bowl, whisk together 1/2 cup hot frying oil, cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt until well combined and smooth.
07 - Brush the prepared Nashville hot sauce generously over both sides of the fried chicken, ensuring full coverage.
08 - Butter the cut sides of the brioche buns and toast in a skillet over medium heat until golden and crisp, if desired.
09 - Place sauced chicken thigh on each bun base. Top with dill pickle chips and a generous amount of coleslaw. Add the bun top and serve immediately.