Pre-heat oven to 180ºC/350F/Gas Mark 4. Grease and line two 18cm (7 inch) sandwich tins.
Sieve the flour, cocoa and Bicarbonate of Soda into a bowl. Add the sugar and mix well.
Make a well in the centre and add the syrup, eggs, oil and milk. Beat well with electric whisk until smooth.
Spoon the mixture into the two tins and bake for 25 - 30 minutes until risen and firm to the touch. Remove from oven, leave to cool before turning out onto a cooling rack.
To make your butter icing, place the butter in a bowl and beat until soft. Gradually sift and beat in the icing sugar and cocoa powder then add enough milk to make the icing fluffy and spreadable.
If the cake has risen a little to high then use a serrated knife to even off the top, now sandwich the two cakes together with the butter icing and cover the sides and the top of the cake with more butter icing.