As soon as Renee  announced that the theme for the third Is My Blog Burning event was to be Cakewalk, this cake came to mind. I think part of the reason is because it just looks sensational. The cake crumb is almost pure black, with hints of the red that's in cacao. The flavor is also dark, slightly bitter yet sweet, from the stout and the unsweetened pure cocoa powder. Amazingly enough though, the texture of the crumb itself is quite light.
I also knew I wanted something to contrast with that black on top. I considered buttercream frosting and cream cheese frosting, but then I thought of plain icing made with icing (powdered) sugar, flavored with lemon. Since the cake is made from Irish stout, by a natural process of association I wondered how a hint of whiskey would work in the icing. Those are the flavors in a whiskey sour after all. It works, indeed.
I originally saw Gary Rhodes making the Irish stout cake on TV. I have modified his original recipe, adding more cocoa powder to up the bitterness. The icing is my addition - he served his version with a whiskey-flavored zabaglione (warm frothy custard sauce). The cake is also nice just unadorned. And if you have leftovers, the black crumbs make a sensational garnish for ice cream sundaes and such.
Note: this is definitely a cake for adults, but you can make it kid-friendly by omitting the whiskey from the icing. The cake itself has no alcohol in it since all of the alcohol in the stout would have dissipated.
Irish Stout Cake with Whiskey-Sour Icing
For the cake:
Preheat the oven to 180° C / 350° F. Butter a 9 x 9 inch / 25 cm square cake pan, line the bottom with parchment paper, and butter and flour the insides of the pan.
Cream together the sugar and butter. (The best way to do this really is with your hands.) Add the eggs and the cocoa powder, mixing well. Add the stout a little at a time (it will foam up quite a bit). Blend well.
Add the sifted flour and the baking powder and baking soda. Mix well. Pour into the pan no more than 2/3rds full. (If you have a smaller pan, put the extra batter into small cake pans, and put in the oven with about 15 minutes to go in the baking.)
Bake for about an hour, until a skewer stuck in the cake about 3 cm / 1 inch from the edge comes out clean. Let cool before putting on the icing.
For the icing:
Mix the lemon juice and the whiskey in the icing sugar - a small whisk is the most usefuil implement for this. If necessary, slowly add a bit of water to the icing, a drop at a time, until you have a thick, smooth paste. Spread this on top of the cake, and let set before cutting it up, into as many or few squares as you feel like.