To make the best chicken parm sandwich, just start with the best chicken parmesan. Our version uses a buttermilk brine for extra juiciness and flavor. We take the leftovers and pack them into a full-sized loaf of toasted ciabatta, adding some extra sauce and cheese to keep the bread moist before cutting it up into single serving slices. This is a chicken parm sandwich so good it's almost worth making the chicken parm fresh just for the sandwich.