I'll be the first to admit that our attempt to duplicate the Stout Float dessert from Back Forty was not a complete and utter success. The foam made by the vanilla ice cream and Guinness was very bitter, a problem fixed by Back Forty with sweet pear and wine syrup (which, not surprisingly, I just didn't have on hand).
Once the drink settles, though and the two elements meld together, you are left with a very creamy and yummy treat. Perhaps the best option is to make a Guinness Shake, adding some milk to the equation – this would exclude the foam problem.
We used Haagen Daz Vanilla, a nice rich tasting selection, but possibly not quite enough of it to match the richness of Back Forty's.
In conclusion, it can be done in the comfort of your own home, and with pleasing results, but if you want a Stout Float that you could have dreams about, fork over the seven dollars and get the real deal.