01 - Whisk together buttermilk, hot sauce, garlic powder, onion powder, salt, and pepper in a large bowl. Add chicken thighs, submerge completely, cover and refrigerate for 2 hours minimum or overnight for maximum flavor penetration.
02 - Combine flour, cornstarch, paprika, baking powder, cayenne pepper, salt, and black pepper in a shallow dish. Mix thoroughly to distribute spices evenly.
03 - Pour vegetable oil into deep fryer or heavy-bottomed pot. Heat to 350°F, maintaining steady temperature throughout frying process for optimal crispiness.
04 - Lift chicken from marinade, allow excess liquid to drip off. Press each piece firmly into flour mixture, turning to coat completely and pressing to create thick, craggy coating that ensures extra crunch.
05 - Carefully lower coated chicken into hot oil using tongs. Fry 6 to 8 minutes per piece, turning once halfway through, until deep golden brown and internal temperature reaches 165°F. Transfer to wire rack to drain excess oil.
06 - Lightly toast burger bun cut sides until golden and warm to the touch.
07 - Combine mayonnaise with hot sauce in small bowl, stirring until smooth. Adjust spice level to preference.
08 - Spread spicy mayo on toasted bottom bun. Layer lettuce leaf, followed by crispy fried chicken, tomato slice, and pickles. Crown with top bun and serve immediately while chicken remains hot and crunchy.