In a large bowl, whisk together 2 cups of buttermilk, 2 tablespoons of hot sauce, 2 teaspoons of kosher salt, and 1 teaspoon of black pepper.

Add 3.5 pounds of chicken pieces to the buttermilk mixture, ensuring all pieces are fully submerged. Cover and refrigerate for at least 4 hours, or overnight.

In a wide shallow dish, combine 2 cups of all-purpose flour, 0.25 cup of cornstarch, 1 tablespoon of smoked paprika, 1 tablespoon of garlic powder, 1 teaspoon of onion powder, 1 teaspoon of kosher salt, and 0.5 teaspoon of cayenne pepper.

Remove chicken pieces from the marinade, letting excess buttermilk drip off. Dredge each piece thoroughly in the seasoned flour mixture, pressing firmly so the coating adheres.

Pour 4 cups of vegetable oil into a heavy cast-iron skillet or Dutch oven, heating over medium-high heat until the oil reaches 350°F (175°C).

Fry the chicken in batches, working with 3 to 4 pieces at a time to avoid overcrowding the pan.

Cook drumsticks and thighs for 12 to 14 minutes and breasts for 10 to 12 minutes, turning occasionally until golden brown and the internal temperature reaches 165°F (74°C).

Transfer the fried chicken to a wire cooling rack set over a baking sheet to drain off excess oil before serving warm.