01 - Combine almond milk and heavy cream in a medium saucepan over medium heat. Warm gently until steaming but do not boil.
02 - Whisk eggs and powdered erythritol in a mixing bowl until the mixture becomes pale and smooth.
03 - Gradually ladle the warm milk mixture into the egg mixture while whisking constantly to prevent curdling.
04 - Return the mixture to the saucepan. Cook over low heat, stirring constantly, until slightly thickened and coating the back of a spoon, approximately 5 to 8 minutes.
05 - Remove from heat and stir in ground nutmeg, cinnamon, and vanilla extract. Add rum or bourbon if using.
06 - Pour into a pitcher or bowl and refrigerate for at least 1 hour until thoroughly chilled.
07 - Pour cold eggnog into glasses. Top with whipped cream and dust with additional nutmeg or cinnamon.