Heat oven to 180C/160C

Grease and line the base of two 18cm sandwich tins.

Sieve 175g self-raising flour, 2 tbsp cocoa powder and 1 tsp bicarbonate of soda into a bowl. Add 150g caster sugar and mix well.

Make a well in the centre and add 2 lightly beaten large eggs, 150ml sunflower oil and 150ml semi-skimmed milk.

Beat well with an electric whisk until smooth.

Pour the mixture into the two tins and bake for 25-30 mins until risen and firm to the touch.

Remove from oven, leave to cool for 10 mins before turning out onto a cooling rack.

To make your butter icing, place 100g unsalted butter in a bowl and beat until soft.

Gradually sieve and beat in 225g icing sugar and 40g cocoa powder then add enough milk to make the icing fluffy and spreadable around 2 ½ tbsp.

Sandwich the two cakes together with the butter icing and cover the sides and the top of the cake with more butter icing.