In a large bowl, toss the chicken with 1 tbsp. kosher salt, the pepper, onion powder and garlic powder. Cover and refrigerate overnight.
Pour 1 inch of oil into a large, deep cast-iron or other heavy skillet. Heat over medium until a deep-fry thermometer registers 350 degrees . In a large bowl, whisk the flour, cornstarch, paprika and 2 tsp. kosher salt. In a medium bowl, whisk the buttermilk and hot sauce.
Working in two batches, coat the chicken in the buttermilk mixture, then dredge in the flour mixture, turning to coat. Fry, turning, until the skin is deep golden and the chicken is cooked through, about 12 minutes; transfer to a wire rack set inside a baking sheet. Chill until ready to eat.