Place each chicken breast between two sheets of plastic wrap and pound to an even 1/2-inch thickness using a meat mallet or rolling pin. This ensures even cooking.

In a large bowl, whisk together the buttermilk, 2 tbsp hot sauce, 1 tsp salt, 1/2 tsp black pepper, 1/2 tsp paprika, and 1/2 tsp garlic powder. Add the pounded chicken breasts, ensuring they are fully submerged. Cover and refrigerate for at least 30 minutes, or up to 4 hours for best flavor.

In a shallow dish or large resealable bag, combine the all-purpose flour, cornstarch, baking powder, 2 tsp salt, 1 tsp cayenne pepper, 1 tsp smoked paprika, 1 tsp garlic powder, 1 tsp onion powder, and 1/2 tsp black pepper. Whisk well to combine, ensuring no lumps.

Pour peanut or vegetable oil into a heavy-bottomed pot or Dutch oven until it's about 3 inches deep. Heat the oil over medium-high heat to 350°F (175°C). Use a meat thermometer to monitor the temperature.

Working one at a time, remove a chicken breast from the buttermilk marinade, letting any excess drip off. Dredge the chicken liberally in the flour mixture, pressing firmly to ensure the coating adheres well. Shake off any excess.

Carefully lower 1-2 chicken breasts into the hot oil (do not overcrowd the pot). Fry for 6-8 minutes, flipping halfway through, until golden brown and cooked through, reaching an internal temperature of 165°F (74°C).

Remove the cooked chicken to a wire rack set over a baking sheet to drain. Immediately sprinkle with a pinch of salt. Repeat with remaining chicken, ensuring the oil returns to 350°F (175°C) between batches. Reserve 1/2 cup of the hot frying oil for the Nashville Hot Oil.

In a small heatproof bowl or saucepan, combine the reserved 1/2 cup hot frying oil with 2-4 tbsp cayenne pepper (depending on desired heat), 1 tbsp brown sugar, 1 tbsp smoked paprika, 1 tsp garlic powder, 1 tsp onion powder, and 1/2 tsp salt. Whisk until smooth.

Generously brush both sides of each hot fried chicken breast with the Nashville Hot Oil mixture. Be thorough to ensure maximum flavor and heat distribution.

Lightly toast the brioche buns until golden. Place a hot chicken breast on the bottom bun. Top generously with dill pickle chips and, if desired, a scoop of coleslaw.

Place the top bun on and serve immediately while hot and crispy. Enjoy your homemade Nashville Hot Chicken Sandwich!