Trim the excess skin from the chicken breast and cut them in half, so you will have 4 pieces of chicken.
Combine the chicken with the pickle juice and water in a large bowl or storage bag. Place the chicken in the refrigerator to marinate for at least one hour or up to overnight for maximum flavor.
Combine the flour, cornstarch, pepper, salt, paprika, chili powder, and sugar in a mixing bowl. Whisk to mix all the dry ingredients together.
In a separate bowl, combine the egg with the milk.
Remove each piece of chicken from the pickle juice marinade and dredge it through the flour mixture. Transfer the coated chicken to the egg mixture and coat both sides. Then place the chicken back in the flour mixture to coat it evenly on all sides.
Place each piece of chicken in the air fryer basket lined with parchment paper. Spray the chicken with oil and set the air fryer to cook at 380 degrees Fahrenheit for 16 to 18 minutes. Halfway through the cook time, remove the basket from the air fryer and gently flip the chicken pieces.
When the chicken is finished cooking in the air fryer, allow the pieces to rest for a few minutes.
Place each piece of chicken on a biscuit and serve warm. To add even more flavor, top the biscuit with butter, jelly, or honey before adding the chicken.