Preheat the oven to 180°C. Butter and flour 3 x 20cm sandwich tins.
Sieve the flour, cocoa and bread soda together into a large bowl. Stir in the sugar.
Whisk the eggs in a large jug. Add the oil, buttermilk and vanilla and mix well. Add the red food dye for dramatic effect and the vinegar. Carefully fold into the dry ingredients.
Divide the coloured batter evenly between the tins. Make a little hollow in the centre of each so they will rise evenly. Bake for 25–30 minutes, until an inserted skewer comes out clean and the cake springs back when pressed. Leave to rest in the tins for 5 minutes before turning out onto a wire rack to cool.
To make the icing, cream the butter with half the icing sugar in a bowl until well combined.
Add the cold cream cheese, vanilla and remaining sugar. Only mix as much as you have to in order to combine the ingredients, as the cream cheese will melt the more you beat it and make your icing runny.
To assemble the cooled cake, lightly dust any loose crumbs off the cakes and keep the crumbs to one side. Place one cake on a serving plate and cover with icing. Top with the second cake and cover that with icing, then top with the third cake.