"This easy recipe is an adaptation of the classic, but is even easier to make. Don't be alarmed by the Guinness® - it's simply used to develop the texture of the cake by making it extra dense and moist. This cake almost ends up pudding-like, and goes down a treat when served with cream or ice cream. This proves that a bakery-quality cake can be made so easily at home!"
Preheat oven to 350 degrees F (175 degrees C). Line a 9-inch cake pan with parchment paper; grease parchment paper.
Combine stout beer and butter in a large saucepan over medium-low heat; heat until butter melts and beer looks glossy, 3 to 5 minutes.
Remove beer mixture from heat; whisk in sugar and 3/4 cup plus 2 tablespoons cocoa powder until dissolved and smooth. Whisk in 1/2 cup plus 2 tablespoons sour cream. Mix in eggs and vanilla extract until well blended. Add baking soda; mix in flour gradually until batter thickens and no lumps remain, about 5 minutes.
Pour batter into the prepared pan.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 40 minutes. Cool cake before serving, at least 4 hours.
You can make a simple icing by blending 3/4 cup confectioners' sugar with 1/2 cup plus 2 tablespoons heavy whipping cream and 1/2 cup plus 2 tablespoons softened cream cheese. This sweet but tangy frosting is the perfect topping for the rich and dark cake.