01 - Combine almond milk and heavy cream in a medium saucepan over medium heat. Warm gently until steaming but do not boil, stirring occasionally to prevent scorching.
02 - Whisk eggs and powdered erythritol in a mixing bowl until the mixture becomes pale in color and completely smooth.
03 - Gradually ladle small amounts of the warm milk mixture into the egg mixture while whisking constantly. This prevents the eggs from curdling and ensures a smooth consistency.
04 - Pour the tempered mixture back into the saucepan. Cook over low heat, stirring continuously with a wooden spoon or whisk, until the mixture thickens enough to coat the back of the spoon, approximately 5–8 minutes.
05 - Remove from heat immediately. Stir in ground nutmeg, ground cinnamon, and vanilla extract until fully incorporated. Add rum or bourbon now if using alcohol.
06 - Transfer the eggnog to a glass pitcher or bowl. Refrigerate for at least 1 hour, or until completely chilled. For extra frothiness, blend before chilling.
07 - Pour chilled eggnog into serving glasses. Top with whipped cream and dust generously with nutmeg or cinnamon before serving.