01 - In a large bowl, combine buttermilk, hot sauce, kosher salt, and black pepper. Submerge chicken thighs and allow to marinate for at least 20 minutes or up to overnight in the refrigerator.
02 - In a shallow dish, combine flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper, and salt to create a seasoned dredge.
03 - Remove chicken from marinade, allowing excess liquid to drip off. Coat each thigh thoroughly in the seasoned flour mixture, pressing to ensure adherence. Set coated chicken on a wire rack and allow to rest for 10 minutes.
04 - Pour vegetable oil into a heavy skillet or Dutch oven to a depth of 1 inch and heat to 350°F. Monitor temperature for consistency.
05 - Carefully add chicken thighs to the hot oil in batches. Fry each side for 5 to 7 minutes, or until golden brown and an internal temperature of 165°F is reached. Place fried chicken on a wire rack to drain excess oil.
06 - In a bowl, whisk 1/2 cup of the hot frying oil with cayenne pepper, brown sugar, chili powder, smoked paprika, garlic powder, and salt until fully combined. Generously brush this spiced oil over both sides of the fried chicken.
07 - If desired, spread unsalted butter onto the cut sides of brioche buns. Toast in a skillet until golden brown.
08 - Arrange sauced chicken on the bottom halves of toasted buns. Top with pickle chips and a generous amount of coleslaw. Complete with top buns and serve promptly while hot.