Serves 12

Nigella Lawson likes to ice the top of the cake so that it resembles the famously frothy head that sits on top of a pint of stout, but she says it also tastes perfectly good if you leave it uniced and plain.

for the cake:

250 ml Guinness

250 g unsalted butter, cubed or sliced

75g cocoa

400 g caster sugar

1 x 142 ml pot sour cream

2 eggs

1 tablespoon real vanilla extract

275 g plain flour

2 1/2 teaspoons bicarbonate of soda

for the topping:

300 g Philadelphia cream cheese

150 g icing sugar

125 ml double or whipping cream

Preheat the oven to 180°C and butter and line a 23 cm springform tin.

Pour the Guinness into a large pot. Add the butter cubes or slices and heat until the butter melts, then whisk in the cocoa and sugar. In a separate bowl, beat the sour cream with the eggs and vanilla, then pour into beer and butter mixture. Lastly, whisk in the flour and baking soda.

Pour the cake batter into the greased and lined tin and bake for 45 minutes to 1 hour. Leave to cool completely in the tin on a cooling rack, as it is quite a damp cake.

When the cake is completely cold, sit it on a flat platter or cake stand to ice it. Lightly whip the cream cheese until smooth, sieve over the icing sugar and then beat them both together. (Alternatively, you can do this in a food processor, putting the unsieved icing sugar in first, and blitz to remove lumps before adding the cheese.)

Add the cream and beat again until it makes a spreadable consistency. Ice the top of the black cake so that it resembles the frothy top of the famous pint.