Pound chicken breasts to about 1/2-inch thickness.
Marinate chicken in pickle juice for 30 minutes to 1 hour (refrigerated).
In a bowl, whisk together milk and egg.
In a separate bowl, mix flour, powdered sugar, paprika, salt, pepper, garlic powder, and cayenne.
Heat peanut oil in skillet or fryer to 350°F (175°C).
Remove chicken from marinade, dip into milk/egg mixture, then dredge thoroughly in the flour mixture.
Carefully place chicken into hot oil and fry for about 3–4 minutes per side or until golden brown and internal temperature reaches 165°F (74°C).
Drain on a wire rack over a baking sheet lined with paper towels.
Butter and lightly toast the buns.
Assemble sandwiches by placing pickles on the bottom bun, adding the fried chicken, and topping with the upper bun.