Refrigerate the cans of coconut milk for at least 12 hours or more. Make sure you do not shake the cans! Once chilled, open the cans and scoop out the thick coconut cream from the top of the cans. You can keep the watery part for smoothies or soups, or discard it.
Vegan whipped cream
Take a large clean bowl, making sure it's completely dry and free of grease. Add the coconut cream and whip with an electric whisk for 2 minutes until light and fluffy. Scrape down the sides of the bowl with a rubber spatula. Add the vanilla extract and whisk to combine.
Sift the powdered sugar and arrowroot powder and add them to the bowl with the whipped coconut cream. Whisk again for another 1-2 minutes until combined.
Serving and Storage
Use immediately to frost cakes, cupcakes, or store in the fridge in an airtight container for up to a week. When ready to serve, you may need to re-whip it again as it will stiffen once chilled.
Full-fat canned coconut milk: Refrigerate the cans of coconut milk for at least 12 hours, and use the thick cream from the top of the cans. This recipe will call for about 2 x 400ml (14oz) cans, depending on the brand. I find Biona and Nature's Charm yield the best amount of coconut cream.
Some white sugar in the US is not vegan, if in doubt use organic sugar.
Do not shake the cans of coconut milk!
Keep frosted cakes in the fridge until ready to serve. I don't recommend leaving cakes with coconut frosting out at room temperature for more than a couple of hours as the frosting could start to melt.