01 - Combine almond milk and heavy cream in a medium saucepan over medium heat. Warm gently until steaming, being careful not to boil the mixture.
02 - Whisk eggs and powdered erythritol in a mixing bowl until the mixture becomes pale and smooth.
03 - Gradually ladle small amounts of the warm milk mixture into the eggs while whisking continuously. This tempers the eggs and prevents curdling.
04 - Pour the tempered mixture back into the saucepan. Cook over low heat, stirring constantly, until the mixture thickens slightly and coats the back of a spoon, approximately 5 to 8 minutes.
05 - Remove from heat and stir in nutmeg, cinnamon, and vanilla extract. Add rum or bourbon at this stage if using alcohol.
06 - Pour the eggnog into a bowl or pitcher. Refrigerate for at least 1 hour until completely chilled.
07 - Pour cold eggnog into glasses. Top with whipped cream and dust with additional nutmeg or cinnamon before serving.