Preheat your oven to 180c and line 2 loose bottom cake tins with baking paper. I've used 20cm cake tins.
Add the apple cider vinegar to your soy milk and stir to combine. Set these aside for 5 minutes to allow them to thicken and create your vegan buttermilk alternative.
In a mixing bowl, combine the sugar and olive oil. Cream these together until pale and fluffy, then whisk through the buttermilk mixture and vanilla.
Sift the dry ingredients, then fold these into the wet ingredients so that you're left with a smooth, lump free batter.
Divide this between your two cake tins and place these into the oven for 30-35 minutes, until golden and well risen. Remove your cooked cakes from the oven and allow to cool on a wire wrack.
Meanwhile, to make the passionfruit syrup, combine the lemon juice, zest passionfruit and sugar in a saucepan and bring these to the boil. As the sugar dissolves, reduce the heat to a simmer and leave this for a few minutes. Remove from the heat and allow to cool.
For the buttercream, beat the butter using an electric hand whisk or stand mixer until pale and fluffy. Gradually add in the icing sugar whilst mixing until fully combined. To neutralise the yellow colour, beat in a few drops of purple food colouring.
Once the cake has cooled, you can begin to assemble to cake. Add a layer of buttercream to one of your cake layers, creating a little dip in the centre. Add in a few spoonfuls of your passionfruit syrup, then place the second cake layer on top.
Use any remaining passionfruit syrup to baste the second cake layer. Coat the cake in a layer of buttercream frosting, using a cake scraper to achieve a lovely smooth finish.
Pop the cake into the fridge for 20 minutes to help the frosting set. Gently melt the chocolate, then drizzle this around the edge of the cake, to create a drip effect. After placing the cake into the fridge, this should allow the chocolate to set quickly.
Take the remaining frosting and add this into a piping bag. Pipe swirls around the edge of the cake- I love to add sprinkles around the edges here too! Decorate each spiral with a macaron and you're ready to serve!
