Instructions

1. Preheat the oven to 180C/350F/gas mark 4. Grease and line a 22cm round cake tin.
2. Stir the flour, cocoa and bicarbonate of soda into a large bowl and stir in the sugar.
3. Combine the butter, vanilla and 250ml water in a saucepan and stir until the butter has melted. Add to the flour mixture and stir well until combined. Add the eggs and beat well until combined.
4. Spoon the cake batter into a tin and smooth the top. Bake for 1 hour 10 minutes, or until a skewer inserted into the middle of the cake comes out clean. Leave the cake in the tin for 5 minutes, then turn onto a wire rack to cool completely.
5. To make the icing, heat the cream in a small saucepan to just before boiling. Remove the pan from the heat and stir in the chocolate until the mixture is smooth and the chocolate has melted. Transfer to a bowl and chill for 2 hours.
6. When the icing is chilled, whip with an electric beater, cut the cooled cake in half and spread one third of the mixture in the centre, and the remaining icing over the outside.