Preheat oven to 180 C/gas mark 4. Butter and flour the sides of two 20cm cake tins and line base with greaseproof paper

FOR THE CAKE: Place chocolate and milk in a bowl sitting over a saucepan of gently simmering water and heat until the chocolate has melted. Make sure the bottom of the bowl does not touch the water. Set aside to cool slightly

Beat the butter until soft then add caster sugar and continue to beat until the mixture is pale and fluffy. Beat in the eggs one at a time then fold in the melted chocolate.

Sift in the flour, cocoa powder, baking powder and bicarbonate of soda and fold in gently to mix. Divide the mixture between the two tins and bake in the oven for about 25 minutes or until a skewer inserted into the middle of each cake comes out clean.

Remove the cakes from the oven and allow to sit for 5 minutes before turning them out of their tins and placing them on a wire rack to cool.

Once cakes are cool, sandwich them together with the chocolate butter icing. Place the cake on a plate or a cake stand and either dust with cocoa powder or make double quantities of the icing and spread over the cake.

FOR THE ICING: Beat the butter, cream and vanilla extract until very soft. Gradually sift in the icing sugar and the cocoa powder, beating all the time until it is all added. Continue to beat until very soft then whisk mixture until it is light and fluffy.