I make these all the time (had posted the recipe from TOH on the old BB last year) and use the different types of kisses. At Christmas I used the red and white striped ones and they looked very festive. I refrigerate the batter for about an hour (have also held it overnite with good results) and it makes the brownies even "fudgier" but the best part - the batter goes into the small mini cups/tins much neater without the dribbles. I've started doing this with anything that goes into muffin cups - regular - and especially the minis.
People really like these - they look great on a dessert table and they are much neater to serve and eat than regular brownies. And - they taste great!!! Great for school parties, too.