Pre heat oven to 175 degrees Celsius. Grease a 3 x 9 inch cake tin with butter, dust with flour and tap out the excess.
In a large bowl, mix together the flour, sugar, cocoa, bi-carb soda, baking powder and salt, sifting once until well combined. Then add eggs, buttermilk, warm water, oil and vanilla. Beat on a medium speed until smooth for 2-3 minutes.
Divide batter evenly among the 3 pans (To achieve the same height, weigh the batter into each pan.) Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean. Cool in the oven for 15 minutes, then turn out the cakes onto wire racks and allow to cool completely.
Prepare chocolate frosting: in a large mixing bowl, cream the butter until light and fluffy. Then beat in the icing sugar half a cup at a time. Gradually add the cocoa powder and vanilla extract. Add enough milk to achieve a frosting consistency to spread between the cake layers.
Assemble cake, spreading a generous amount of frosting between the layers and on top.
Prepare marshmallow frosting: place egg whites, sugar and cream of tartar in a heatproof bowl. Set over a saucepan with simmering water. Whisk constantly for 3-4 minutes, or until sugar is dissolved and the egg whites are warm to the touch.
Remove from saucepan and place on bench. Beat with an electric mixer on low speed for 5-7 minutes or until glossy peaks form. Add vanilla extract and mix until combined. Use straight away to pipe the ghosts on the cake. Apply candy eyes.
Happy Halloween. Enjoy!