In this recipe it is VERY important that you cut the chicken breasts in half and pound them to make them flatter. The reason for this is that breasts tend to be quite thick and it takes a lot longer to cook them if they are thick than if they are thin. Long cooking times tend to lead to dried out meat which doesn't do breast meat any favors as it's a leaner cut to begin with. By pounding the breasts into 1/2" thick pieces, you are greatly reducing the time it takes to cook them and minimizes the chance that the meat will become overcooked and dry tasting.