Separate the eggs carefully. No egg white should be mixed with the yolks.
Add the xylitol and the vanillas to the egg yolks in a mixing bowl and beat until it forms a white, almost stiff mixture.
Heat half the cream (500 ml) to just below boiling point (while keep beating the egg and xylitol mixture). Slowly add the hot cream to the egg and xylitol mixture using a soup ladle. Add a pinch of salt.
Allow mixture to cool in the refrigerator for at least 12 hours.
Once the custard has cooled for 12 hours in the fridge, the remaining 500 ml cream should be whisked to stiff peaks.
Fold the reserved whipped cream into the chilled custard. Then place it in a suitable container and store in the freezer overnight.