01 - Combine buttermilk, hot sauce, kosher salt, and black pepper in a large bowl. Submerge chicken thighs and marinate for at least 20 minutes or up to overnight in the refrigerator.
02 - In a shallow dish, mix together all-purpose flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt until evenly combined.
03 - Remove chicken from marinade, allowing excess liquid to drip off. Coat each thigh thoroughly in the flour mixture, pressing to ensure adherence. Set coated pieces on a wire rack and let rest for 10 minutes.
04 - Pour vegetable oil into a large, heavy skillet to a depth of one inch. Heat oil to 350°F (175°C), monitoring with a thermometer.
05 - Working in batches, fry chicken thighs for 5 to 7 minutes per side until golden and crisp. Check internal temperature reaches 165°F (74°C). Transfer cooked chicken to a wire rack.
06 - In a medium bowl, combine 1/2 cup hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt. Whisk until blended. Generously brush sauce on both sides of the fried chicken.
07 - Optional: Lightly butter the cut sides of brioche buns and toast face-down in a skillet until golden brown.
08 - Layer sauced chicken on the bottom half of each bun. Top with dill pickle chips and a generous portion of coleslaw. Cap with the remaining bun and serve immediately.