Classic chocolate cake

Grease and line the base of two 22cm round cake tins.  Preheat the oven to 180°C (160°C fan, gas mark 4)

Put the butter and both sugars into a bowl and beat together with an electric whisk until light and fluffy.  Add the eggs one at a time, beating well between each addition.

Sieve the flour, cocoa, baking powder and bicarbonate of soda into the mixture, then pour in the buttermilk.

Stir everything together to create a smooth mixture and spoon into the prepared cake tins.

Bake for 20-25 minutes until just firm and shrinking away from the sides.

Cool in tins for 5 minutes then turn on to a wire rack to completely cool.

Sieve the icing sugar and cocoa into a bowl, then add the butter and 3tbsp of boiling water.  Stir together to make a smooth spreadable consistency.

Spread half of the icing on to the base of one chocolate sponge, sandwich together with the other chocolate sponge.  Spread the remaining icing over the top of the cake, using a palette knife dipped in hot water.  Sprinkle over grated chocolate to decorate.