Melt the butter.
Fit the K beater to the machine.
Pre heat the oven to 180ºC.
Line the cupcake tin with cupcake cases.
Add Ingredients 1 (stout, butter, cocoa powder, caster sugar) into the Mixer bowl.
Attach the Mixer bowl to the machine and fit the splash guard.
Mix on speed 1 for 2 minutes.
Add Ingredients 2 (sour cream, eggs, vanilla) to the bowl.
Mix on speed 2 for 1 minute.
Add Ingredients 3 (flour, bicarbonate of soda) into the bowl.
Evenly spoon the batter into the cupcake cases.
Bake for 15 minutes at 180ºC.
Leave to cool on a wire rack.
Retrieve, clean the Mixer bowl and fit the Whisk tool.
Add Ingredients 3 (cream cheese, icing sugar, cream) into the Mixer bowl.
Mix on speed 5 for 1 minute.
Spoon the icing onto the cakes.
Serve.