This cake is a favourite of teen baker Elizabeth Fryer. It is very easy to make and always tastes terrific. I have adapted the recipe from Nigella Lawson's cookbook Feast.

1 cup Guinness beer

1 cup unsalted butter

3/4 cup unsweetened cocoa powder

2 cups sugar

2/3 cups sour cream

2 large eggs

1 tablespoon vanilla

2 cups all-purpose flour

2 1/2 teaspoons baking soda

Garnish:

Icing sugar or whipped cream

Preheat oven to 350 F.

Butter a 9-inch spring-form pan and line bottom with parchment paper.

Pour Guinness into a large saucepan over medium heat. Add butter and heat until melted. Remove from heat, whisk in cocoa powder and sugar and reserve.

Combine sour cream, eggs and vanilla in a separate bowl and beat until uniform. Add sour cream mixture to Guinness mixture and whisk to combine.

Whisk in flour and baking soda. Pour batter into prepared pan and bake for 50 minutes to 1 hour, or until a cake tester comes out with crumbs clinging to it.

Place tin on a rack and leave to cool completely. Before serving, dust with icing sugar or lightly sweetened whipped cream. Serves 8 to 10.