Whisk together the Kahlua through cornstarch and put in a medium size sauce pan over medium-high heat.
Bring to a boil, reduce heat to medium and whisk until consistency thickens – should only take a minute or two.
Trim chicken of any fat (some people do, some people don’t but it’s definitely a DO for me).
Poke holes in the chicken using a fork, then put in a large plastic bag. Pour in the marinade, seal and flip it around a couple of times to make sure it’s coated. Refrigerate and let it marinate for a couple of hours. Even if you don’t have time to marinate it that long, it will still be good. Just do it next time
Preheat grill to medium, and of course do your usual scrubbing the grates, etc. Grill for a few minutes on each side, until done all the way through.