01 - Combine buttermilk, hot sauce, salt, and pepper in a large bowl. Submerge chicken thighs and marinate for a minimum of 20 minutes or up to overnight under refrigeration.
02 - In a shallow dish, mix flour, cornstarch, paprika, garlic powder, onion powder, cayenne, and salt until well blended.
03 - Remove chicken from marinade and let excess liquid drain. Dredge each thigh in the seasoned flour mixture, pressing to ensure an even coating. Transfer to a wire rack and let rest 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.
05 - In batches, fry dredged chicken thighs for 5 to 7 minutes on each side until golden brown, crisp, and cooked through to an internal temperature of 165°F. Drain on a wire rack.
06 - In a medium bowl, whisk 1/2 cup hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt until fully combined. Brush generously over both sides of hot 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 sauced chicken thighs on the bun bottoms, add dill pickle chips and a generous scoop of coleslaw, then finish with the top buns. Serve immediately while hot.