Pre-heat the oven to 180°C/350°F/Gas Mark 4. Line 2 x 8” round cake tins with parchment paper
Beat together the Original Whirl Butter Alternative, sugar, oat milk, egg replacer and half the lime zest and juice.
Add the flour, courgettes, bicarb and baking powder. Stir until all the ingredients are combined.
Divide the mixture between the prepared tins place in the oven for 25-30 minutes until golden and a cocktail stick comes out clean.
Leave to cool in the cake tins for 15 minutes.
Mix the remaining lime juice with the icing sugar, add the zest and pour over one of the cakes whilst it is still warm.
When the cakes have cooled slightly, remove from the tin and transfer to a wire rack to cool completely.
Spread the un-iced cake with the lime curd and place the iced cake on top.