Preheat the oven to 180C / 350F / gas mark 4.
Line 2x 6 inch cake pans with baking paper.
In a jug, mix together half of the soy milk and half of the lemon juice and leave to curdle.
Sift half of the flour and half of the cocoa powder into a mixing bowl and add half of the sugar and half of the baking soda.
Add the the vegan buttermilk, half of the oil, half of the vinegar, half of the vanilla extract and half of the red gel food colour to the dry ingredients and mix until just combined.
Divide the batter between the two tins and bake for 25 - 30 minutes or until they are bouncy to the touch and/or a skewer inserted into the centre of one of the cakes comes out clean.
Let the cakes cool in their pans for 5 minutes before turning them out on to a cooling rack.
Repeat the instructions above to make another 2 layers.
While the cakes are cooling, add the butter and cream cheese into a mixing bowl and beat until creamy and smooth.
Add in the icing sugar 100g at a time until it is thick but spreadable.
Once the cakes are completely cool frost with your own design.