To make the sponges, sift the flour and black cocoa powder in a large bowl, add the bicarb of soda and sugar, and mix well.
In a separate bowl, combine the oil, buttermilk, eggs, vinegar and vanilla extract.
Mix the wet ingredients with the dry ingredients using a spatula, until you get a smooth batter.
Butter and flour 2 cake tins with the diameter of 19 cm/ 7.5 inches - mine have detachable walls and removable bottom which helps a lot.
Divide the mixture evenly between the 2 tins and bake in the preheated oven at 180 degrees Celsius (350 Fahrenheit) for 35 minutes or until a skewer inserted in the middle comes out clean.
Remove from the oven and leave to cool completely.
To make the frosting, sift the icing sugar and add it to a food processor together with the soft butter, food colouring, vanilla extract and milk.
Mix until you get a smooth paste, then add the cream cheese and mix again.
When the sponges are cool, spread cream over one sponge, top with the second sponge, and spread more cream on the top and sides.
Decorate with more icing or Halloween decorations.