Refrigerate panna cotta, uncovered, until cool, then cover with plastic wrap and leave in refrigerator until set, at least 3-4 hours but ideally overnight (depending on the size of your vessel).
NOTE: This recipe was made to be lower in carbs, but you can replace the xylitol for sugar if you prefer! For the panna cotta, heat the cream, milk and xylitol in a pot. Remove form the heat before it ...