A Small Victory calls it Heaven in an Ice Cream Bowl and some say it originated with Dan; I'll say no more than to lead you on with just this much of a teaser:

Let the mixture cool completely, stir in the Guinness, and freeze the mixture in an ice-cream freezer according to the manufacturer's instructions.

and let you check the recipe yourself. Weird as it sounds, Google found a keg of alternatives For my own sense of adventure, iced cappaccinos are one thing and maybe a chocolate malted and a chocolate malt are not all that dissimilar, but this bit of home chemistry sounds to me dangerously close to a waste of a perfectly good half-cup.

Then again you never know ...