Make the Cake
This portion of the recipe can be made ahead and allowed to sit at room temperature for 2 days

Preheat oven to 350º

Line twelve 3" diameter pastry rings with parchment paper that extends up the sides of the rings and above about 1 inch. Make a bottom for the rings using tin foil. This cake batter is very wet, so the rings will leak if the bottom is not lined. Place prepared rings on a flat baking sheet. (If you do not have rings, you may use lined cupcake tins, or a 9” round or square cake pan with 3” sides, buttered & lined with parchment paper)

Melt the butter and Guinness in a large pot over medium-high heat. Whisk in the cocoas and sugar

In a separate bowl, over medium-high heat, whisk the sour cream, eggs and vanilla. Add to the butter mixture

Whisk in the remaining dry ingredients to blend, then pour into prepared rings (? cup per ring) or pan. Bake for 20-25 minutes with rings or cupcake tins (bake 45-50 minutes in a cake pan) Test with toothpick for doneness

Cool thoroughly before removing from rings/pan, about 45-50 minutes


Prepare the Sabayon

In a stainless bowl, whisk yolks with the sugar and salt, then add liqueur and water

Place bowl over a simmering water bath and continue whisking until mixture has thickened, 2-3 minutes

Remove from heat and whisk in melted chocolate, then place bowl over an ice bath, whisking occasionally until the mixture has cooled, about 1-2 minutes

Fold in the whipped cream


Assemble
Press each cake (or a piece of cake) into a small, clear drinking glass

Top with sabayon. It will actually look like a pint of Guinness!