Preheat the oven to 180 degrees C. Line a 20cm square baking tin with parchment.
Place all the cake ingredients into a large bowl and beat using an electric hand beater until just smooth and pale. Pour into the prepared cake tin and bake for 55-65 minutes until a skewer comes out clean when inserted into the middle of the cake. Allow to cool completely before decorating.
Place on a serving plate and cover with the vanilla icing. Cut the KitKat in half and stick into the cake to make tombstones. Write on the tombstones in white icing and top with your favourite ghoulish sweets.