In a saucepan over medium heat, bring 1 ½ cups of the heavy whipping cream, butter, and the Lakanto powdered sweetener to a low boil.
Remove the mixture from the heat and whisk in the xanthan gum a little at a time until smooth.
Whisk in the vanilla extract and remaining heavy whipping cream.
Pour the mixture into a loaf pan and chill in the fridge for 2 hours.
Stir the mixture and transfer it to the freezer.
Freeze until solid before serving.