I love eggnog, but I hate how most people make it. I hate raw eggs in my drinks. For years now I've been making my eggnog in a tempering process, where the egg yolks are beaten into the milk mixture, under controlled heat in order to cook the egg yolks without turning them into omelets. What you get in the end is something very similar to a creamy liquified custard. This is the only way I've ever made eggnog, I've never tried the raw egg route, simply because the sound of raw eggs in my dessert beverages sounds icky!
In a large sauce pan over medium heat, bring milk and cream to simmer. Add the cinnamon and nutmeg and be sure to stir occasionally to avoid scorching the milk.
Add confectioner's sugar to the milk/cream mixture. Beat until sugar is dissolved. (Add more or less sugar depending on how sweet you like your nog.)
In a large mixing bowl beat the 12 egg yolks together until frothy.
Once milk/cream mixture is simmered, spoon out 1 tablespoon of the simmered milk/cream into the egg yolks, and beat the egg yolks vigorously. Repeat this process four times; spooning a tablespoon of hot milk/cream into the bowl with the egg yolks, then beating the egg yolks vigorously.
(This is tempering the egg yolks. For best results start with room temperature eggs.)
Pour the rest of the hot liquid over the egg yolks and beat vigorously until the entire mixture is good and incorporated.
Mix in vanilla and rum.
Beat vigorously to fully incorporate the ingredients.
Cool off at room temperature, then bottle it until jugs and chill before serving. Be sure to shake the containers well to remix the spices back into the beverage before serving.