01 - Pound chicken breasts between parchment paper to even 1/2-inch thickness for uniform cooking.
02 - Whisk buttermilk with salt, pepper, garlic powder, and paprika. Submerge chicken and refrigerate 30 minutes to 4 hours.
03 - Combine flour, cornstarch, salt, paprika, and cayenne in a shallow dish for even dredging.
04 - Pour vegetable oil 2 inches deep in skillet or Dutch oven. Heat to 350°F for optimal frying temperature.
05 - Remove chicken from marinade, shake excess liquid. Press firmly into flour mixture, ensuring thick, even coating.
06 - Fry chicken 4-5 minutes per side until golden brown and internal temperature reaches 165°F. Drain on wire rack.
07 - Blend mayonnaise and Dijon mustard until smooth and creamy.
08 - Spread sauce on toasted buns. Layer lettuce, fried chicken, pickles, and tomato. Crown with bun top and serve.