- Preheat the oven to 170°C /325°F/gas mark 3. Line the base of a 30cm round spring form tin with baking parchment.
- To make the cake, heat the butter in a large saucepan over a medium heat until melted. Stir in the Guinness, then remove from the heat and stir in the cocoa powder.
- In a large mixing bowl, whisk together the eggs, sugar, vanilla essence, and buttermilk and then slowly add the Guinness mixture, whisking all the time.
- In a separate large bowl, sieve together the flour, bicarbonate of soda and baking powder. Using an electric whisk, slowly pour the wet mixture into the dry ingredients and keep whisking until it is all well combined.
- Transfer the mixture into the cake tin and bake for approximately 45 minutes. Test to make sure the cake is cooked by inserted a dry skewer into the middle of the cake – if it comes out clean, the cake is cooked. Set aside to cool a little, and then remove from the tin and allow to cool completely on a wire rack.
- Meanwhile, make the icing by blending all the ingredients together using an electric hand whisk until light and fluffy.
- Place the cooled cake on a plate and generously spread the icing on top. The cake will keep for up to 1 week in an airtight container.
- 260g/2¼ sticks plus 1 tbsp unsalted butter
- 300ml/1¼ cups Guinness
- 100g/1 cup cocoa powder
- 2 eggs
- 420g/2 cups plus 2 tbsps caster/superfine sugar
- 2 tsps vanilla essence
- 180ml/¾ cup buttermilk
- 300g/2½ cups plain/all-purpose flour
- 2 tsp bicarbonate of soda
- 1 tsp baking powder
For the icing
- 100g/7 tbsp unsalted butter, softened
- 300g/2½ cups sifted icing/confectioners’ sugar
- 1 tsp vanilla essence
- 300g/1¼ cups full-fat cream cheese
Makes 1 cake serves 10