Preheat your oven to 180c fan and line a 23cm square baking tin with baking paper.
Combine the soy milk and apple cider vinegar and mix well. Set these aside for 5 minutes to allow to thicken and create a vegan buttermilk.
In a large mixing bowl, beat together the sugar and olive oil until pale and fluffy. Then, whisk in the buttermilk mixture and vanilla extract.
Sift the dry ingredients and fold these through the wet mixture to create a smooth batter.
Pour the batter into baking tin and bake for 30-35 minutes, until golden and nicely risen. Remove the cake from the oven and transfer to a wire wrack to cool completely.
For the buttercream frosting, start by beating the butter using an electric hand whisk or stand mixer. Once pale and fluffy, begin gradually adding in the icing sugar and vanilla until fully incorporated.
Slice the cooled cake into portions, then pipe swirls over the top. Add your favourite fresh fruits and decorations to finish!