Yeah, this is one of my favorites.

Oatmeal stout is one of the sweetest stouts. It maintains those mellow, chocolatey undertones without having all the hoppiness (if you're hoppy and you know it... ) i.e. bitterness. A barley-based stout (like Guinness) would be interesting, but I'd want to make some adjustments flavor-wise...or maybe pair the cake with...something - (raspberry?) sounds like one to mull over.

For individual cakes (I'm thinking a little larger than 2" dia.), I'd bake for 15 to 20 minutes.