In a medium saucepan, whisk together the coconut milk, creamer, and sugar. Sprinkle the agar over the top and whisk vigorously to incorporate, being sure not to leave any lumps. Turn the stove up to medium heat and cook until the mixture comes to a full boil, stirring gently from time to time.
Remove the pan from the heat and whisk in the vanilla. Cool to room temperature before stashing it in the fridge. Thoroughly chill for at least 3 hours, until completely solid—you should be able to trun the entire pot upside down and nothing will fall out (but don't hold it like that for too long, just in case!)
Scrape the disk of solidified whipped cream out of the pan and into your food processor or blender. Thoroughly purée, scraping down the sides and bottom of the bowl, until completely smooth. At first, it will seem dry and grainy, but just give the machine enough time to work out the lumps. Once silky and soft, dollop it onto desserts with a spoon or move it into a piping bag to give it a more "polished" look.