01 - Combine almond milk and heavy cream in a medium saucepan over medium heat. Warm gently until steaming, but do not let the mixture come to a boil.
02 - Whisk eggs and powdered erythritol in a mixing bowl until the mixture becomes pale yellow and smooth in texture.
03 - Slowly ladle small amounts of the warm cream mixture into the egg bowl, whisking continuously. This gradual process prevents the eggs from scrambling and ensures a smooth custard base.
04 - Return the combined mixture to the saucepan. Cook over low heat, stirring constantly with a whisk or wooden spoon. Continue for 5-8 minutes until the eggnog coats the back of a spoon and thickens slightly.
05 - Remove from heat immediately. Stir in ground nutmeg, cinnamon, and vanilla extract until fully incorporated. Add rum or bourbon at this stage if desired.
06 - Transfer the eggnog to a bowl or pitcher. Refrigerate for at least 1 hour, or until completely cold. The mixture will continue to thicken as it cools.
07 - Pour chilled eggnog into glasses. Top generously with whipped cream and dust with extra nutmeg or cinnamon before serving.