Begin by marinating the chicken breast halves. In a large mixing bowl, combine the pickle juice and water. Add the chicken breasts to the marinade, ensuring they are fully submerged. Cover and refrigerate for at least 1 hour, or up to overnight for maximum flavor.
In a separate bowl, whisk together the milk and egg until well combined. This will be used to dip the chicken before coating it in the flour mixture.
In another large bowl, whisk together the all-purpose flour, powdered sugar, paprika, black pepper, chili powder, salt, baking powder, and cayenne pepper (if using). This will give the chicken its signature crispy coating.
In a deep frying pan or Dutch oven, pour in enough oil for frying (about 2 inches deep). Heat the oil over medium-high heat until it reaches 350°F (175°C). Use a thermometer to check the temperature for perfect frying.
Once the chicken has marinated, remove it from the pickle juice mixture and pat dry with paper towels. Dip each chicken breast into the egg mixture, then coat it thoroughly with the flour mixture. Shake off any excess flour.
Carefully place the coated chicken breasts into the hot oil, being cautious not to overcrowd the pan. Fry for about 4-5 minutes per side, or until the chicken is golden brown and reaches an internal temperature of 165°F (74°C). Use a wire rack to drain the excess oil after frying.
Toast the hamburger buns if desired. Spread a generous amount of mayonnaise on the bottom bun, followed by the fried chicken, pickles, lettuce, tomato, and cheese slices. Top with the other half of the bun.
Serve the sandwiches warm with your favorite sides. Enjoy the incredible taste of your homemade Chick-fil-A Crispy Chicken Sandwich copycat!
