Heat a small saucepan over the stove with the coconut milk and tapioca / arrowroot
When it thickens, whisk over the heat for 1 minute.
Pour the big blob into a bowl and pop some baking paper over its surface.
Pop in the fridge until it cools (2 hours)
Then once it’s cooled you can make the icing
Pop into a kitchenAid mixer or using handbeaters, whip the butter until a couple of shades paler.
Add vanilla powder and sugar and beat on high for 30 seconds
Then add the blobby cold thick coconut milk / flour mix and the 2 tsp lime/ lemon juice
Beat on high for 1-2 minutes until well combined and the texture is a marshmallow whipped texture.
You’re done. Pop in the fridge for 30 minutes before working with it. It’s going to be easier once thickened a little. It will set really nicely and not spill or wobble so pop in the fridge and take out a couple of hours before serving so the butter isn’t hard any more.