Blend chicken breast in a food processor until smooth.
Mix in salt, white pepper, garlic powder, and onion powder.
Shape into thin, large patties (match your bun size) with oiled hands.
Place patties on parchment paper and freeze for 15-20 minutes until firm.
Mix flour, cornstarch, and spices in a bowl.
Coat patties in dry mix, then dip into a wet batter (mix dry ingredients with cold water).
Fry in hot oil (medium heat) for 4-5 minutes per side until golden brown.
Let them rest on a wire rack to stay crispy.
Mix all sauce ingredients in a bowl until smooth.
Refrigerate until ready to use.
Toast the burger buns lightly.
Spread Big Mac sauce on the bottom bun.
Add lettuce, a cheese slice, and a fried chicken patty.
Place the middle bun layer and repeat with sauce, lettuce, pickles, and another patty.
Top with the final bun.