Put the dry ingredients into a mixing bowl - flour, sugar, baking powder and non-butter spread (treat spread as 'dry' for our purposes). Mix until you have an even sandy consistency.
Measure out the coconut milk, egg and vanilla in a jug and beat well. Drizzle into the flour whilst mixing, until you have a smooth batter/mixture. Zest all limes and place three of the lime zest into your mixture. Reserve the other lime zest for the icing. Blend the mixture for ten seconds on high then stop the mixer and clean down the blade.
Spoon evenly into 12 cupcake cases and bake at 170°C for 20 minutes until they bounce back to the touch.
Cool on a wire rack and in the meantime make the icing by mixing the icing sugar, non-butter spread, coconut milk and final lime zest together for several minutes until very light and fluffy.
Pipe the icing on top of the cakes using a reusable piping bag and large star nozzle and sprinkle with the toasted coconut shreds. Amaze your diary-free friends with the most delicious cupcakes they've ever had!