Place the cream and water in to a saucepan and bring to the boil - immediately switch off.
Whisk the eggs, xylitol and cacao powder until aerated.
Pour the hot cream into egg mixture, whisking gently as you pour.
Return mixture to the pot and cook over low heat, stirring for about 3 minutes until its slightly thickened and coats the back of a wooden spoon.
Strain into a container and drink chilled. Thickens slightly on cooling and the egg taste disappears completely, but can also be drunk warm.
Store in the fridge for up to 5 days or freeze for up to a month. Once frozen, it can be whipped for a minute on high speed in a blender or food processor for a delicious healthy ice cream.