Place the halved chicken breasts in a ziplock bag and pour the buttermilk into the bag. Squeeze the air out and seal the bag. Let marinate in the refrigerator for 30 minutes minimum up to several hours.
In a shallow bowl combine the panko breadcrumbs, flour, baking powder, and spices.
Remove the chicken breasts from the buttermilk with a fork, shake off excess buttermilk, and dredge in the breadcrumb mixture to coat on all sides. Spray with oil spray from both sides.
Put the chicken breasts in one layer in the Airfryer basket and air fry at 375F (190C) for 10-12 minutes in total until internal temperature reads 175F (79C) and the chicken breasts are golden brown and crispy. Flip the chicken with a fork or cookie spatula after 5 minutes and spray with more oil if needed.
While the chicken is cooking, make the chicken sauce by combining all the ingredients in a bowl. Then make the slaw by combining shredded cabbage, vinegar, sugar and salt in another bowl. Let the slaw sit for 2 minutes then add ¼ cup of the sauce you made before and stir until combined.
Then brush the cut sides of the Sandwich Rolls with butter and heat a large skillet over medium heat. Toast rolls buttered side down until browned and crisp, about 1 minute.
To assemble the sandwiches, spread some sauce on the bottom roll, place a fried chicken breast on top, and top with slaw.