Pre-heat the oven to 180°C. Prepare three 15cm loose based cake tins by brushing the insides with rapeseed oil and placing a circle of greaseproof paper in the bottom of each.
In a large bowl, whisk together the baking soda and vinegar, then add in the rapeseed oil, apple sauce, oat milk, sugars and golden syrup. Mix together. Add in the grated carrot and stir thoroughly.
In a separate bowl sieve together the salt, baking soda, baking powder, cinnamon, ground almonds and gluten free flour. Fold the dry ingredients into the wet, ensuring they are fully incorporated, then add in the chopped walnuts and raisins and stir through.
Divide the mix equally between the three cake tins. Bake for 40 minutes before inserting a skewer or knife into the centre of each cake. If the skewer comes out clean then the cakes are baked, otherwise return to the oven and check again after five more minutes. Remove from the oven and allow to cool for 5 minutes before removing carefully from cake tins. Once removed allow the cakes to cool completely before icing.
To make the icing, take the cream cheese out of the fridge one hour before using so that it is slightly softer and ensure your vegan butter is soft too. Use an electric stand mixer with the paddle attachment to beat the butter until smooth. Then add in the cream cheese and beat on a low speed until fully combined. You may need to stop the machine and scrape down the sides before beating again to ensure everything is fully mixed. Be careful not to beat on too high a speed as the mixture may split. Add in the icing sugar then beat on a medium speed until combined fully before stirring through the chopped watercress.
Once your cakes are cooled completely, use the icing to cover each layer before stacking, finishing with a thick layer of icing on top. Add fresh edible flowers and/or chopped nuts to decorate.