Step 1

Pour 1/2 cup of the buttermilk, 1/4 cup pickle brine, 1 tablespoon hot sauce, 1 1/2 teaspoons of the kosher salt, 1/2 teaspoon of the black pepper, and 1/2 teaspoon of the garlic powder in a gallon-size zip top bag or large food container and whisk to combine. Add 6 boneless, skinless chicken thighs and flip the chicken to evenly coat. Seal or cover and marinate in the refrigerator for at least 2 hours or up to overnight.

Step 2

Place 1 1/2 cups all-purpose flour, 2 tablespoons cornstarch, the remaining 2 teaspoons kosher salt, remaining 2 teaspoons black pepper, remaining 1 1/2 teaspoons garlic powder, 1 teaspoon cayenne pepper, and 3/4 teaspoon paprika in a medium bowl or shallow bowl and whisk to combine. Place the remaining 1/4 cup buttermilk and 2 large eggs in a shallow bowl and whisk to combine, the mixture will be thick and look slightly curdled.

Step 3

Heat about 4 cups vegetable oil in a Dutch oven or large cast-iron skillet (the oil should come 1 inch up the sides) over medium-high heat until 350°F. Meanwhile, fit a wire rack in a rimmed baking sheet. Bread the chicken one piece at a time: Remove from the buttermilk mixture, dip in the egg mixture to coat, and dredge it in the flour mixture, pressing to make it stick and get into all the nooks and crevices. Place on a rimmed baking sheet or large plate in a single layer.

Step 4

Fry the chicken 2 to 3 pieces at a time: Place in the hot oil and fry until the chicken is cooked through and an instant-read thermometer inserted into the thickest piece registers at least 165°F, 3 to 4 minutes per side. Transfer to the rack. Keep warm in a 200°F oven until ready to serve if desired.

Step 5

Split and lightly toast 6 brioche hamburger buns. Divide and spread 1/2 cup mayonnaise onto the cut sides of the buns (scant 2 teaspoons per piece). Place 3 to 4 pickle chips and 1 fried chicken thigh on each bottom bun. Close with the top bun.