Open the cans of cold coconut milk and scoop out the solid coconut cream that should have formed on top. Save the remaining liquid for use in another recipe (like a smoothie).
Over a large mixing bowl, place a thin cloth napkin or several layers of cheesecloth. Pour the coconut cream over it and lift the napkin to gently squeeze out some of the liquid. The coconut cream will look like a ball of soft cheese.
Discard the liquid from the bowl, then combine the cream, syrup, and probiotic powder in it. Transfer to a sterile, lidded glass dish and keep in a warm place for 24 hours.