- 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