Set you immersion circulator to 160f (71.1c)
Combine all the spices in a small bowl (Sugar, cinnamon, clove, nutmeg, salt, and xanthan gum-if you're using that ingredient) Give it a mix to combine.
separate the egg whites from the yolks and place the yolks in a blender.
on low/medium low blend the egg yolks till they take on a pale yellow color. As soon as that happens add the sugar/spice mixture a little a t a time till you've added it all.
Next add the milk and continue to blend for another 30 seconds.
pour your milk/egg mixture in a freezer friendly zip lock bag then add the cream that the recipe calls for. Give the bag a little shake to mix everything well.
Remove as much air out of the bag as possible, place into the 160f (71.1) water bath, and clip the bag to the side. Cook for 30 minutes. Agitate the bag a few times during the cooking process to ensure that everything cooks evenly. I like to agitate every 10 minutes.
After it cooks place the bag in an ice water bath and chill the egg nog mixture.
Once your egg nog is chilled, transfer to a glass jar. Add the vanilla, and if you plan on adding alcohol you can add that now. Mix well and refrigerate overnight.