Looks like the stout has just enough sugar in it to get a nice browning...
Not to be the typical board know it all but have you considered tucking those wing tips in under the bird? That really helps it cook more evenly and gets the entire breast dark and crisp.
This post was edited on 11/23 12:47 PM by backcountry mounty
Thanks man! I added 4 12oz bottles of Guinness to my regular cider brine - two right before I brought it to a boil, two right after I took it off the burner. Don't worry, there were plenty of other quaffable options available during the process, all of which were consumed.