Slice the chicken breasts in half horizontally to make 4 thinner cutlets. If needed, lightly pound them to an even thickness.

In a bowl, whisk together the buttermilk, hot sauce, paprika, garlic powder, onion powder, salt, and black pepper. Add the chicken and turn to coat. Cover and marinate for at least 20 minutes, or up to 4 hours in the refrigerator.

In a separate bowl, mix the flour, cornstarch, cayenne pepper, smoked paprika, and baking powder.

Remove the chicken from the marinade, letting any excess drip off. Dredge each piece in the flour mixture, pressing firmly so the coating adheres well. For extra crunch, dip the coated chicken briefly back into the marinade, then dredge in the flour mixture again.

Heat 1 to 2 inches of vegetable oil in a deep skillet or Dutch oven to 350°F. Fry the chicken in batches for 4 to 6 minutes per side, or until golden brown, crisp, and cooked through to 165°F internal temperature.

Transfer the chicken to a wire rack or paper towels to drain.

In a small bowl, stir together the mayonnaise and hot sauce to make a spicy spread.

Assemble each sandwich by spreading the spicy mayo on the toasted buns, then layering with lettuce, fried chicken, pickles, and tomato if using. Top with the other bun half and serve immediately.