Preheat the oven to 325° F / 160° C / 140° Fan / Gas 3.

Grease & line 2x 10" round cake tins.

Cream together the butter, oil and sugar until pale and creamy.

Slowly add the beaten eggs and vanilla and mix well.

Finally add the flour, cocoa powder and milk and mix thoroughly until smooth.

Carefully divide the batter evenly into the 2 tins, weighing the tins will help to get them as even as possible.

Bake for around 70 minutes or until a skewer inserted comes out clean.

Turn out of the tins and leave to cool on a wire rack.

Mix together the icing sugar, cocoa powder and the softened butter until creamy and lump free.

Then add the vanilla and milk. Add the milk 1 tbsp at a time until you achieve a good creamy consistency.

Once the cakes are cool slice the crust off of each one so they are level and sandwich the 2 together with some of the buttercream and then use the rest to cover the cake ready for decorating or covering in fondant.