• Start with separating egg yolks and egg whites, each into a medium mixing bowl. Keep egg whites covered in the refrigerator for later.

Raw Eggs Method

• Add the sugar to the egg yolks. Whisk until it is creamy, and all the sugar has dissolved. 
• Whisk the milk, half-n-half, vanilla extract, salt, nutmeg, and cinnamon into the yolk mixture until well combined. Then whisk in the bourbon.
• If serving the eggnog later, cover the milk mixture with plastic wrap and refrigerate it until you're ready to serve. (Otherwise, proceed to the next step.)
• Remove the egg whites from the refrigerator. Beat until stiff peaks form using a whisk or a hand mixer.
• Slowly add 1 cup of the milk mixture to the egg whites. Fold in the egg whites with a rubber spatula. Then add the rest of the milk mixture to egg whites and mix well.

Cooked Eggs Method

• Add the milk, half-n-half, nutmeg, cinnamon, and salt to a saucepan. Place over medium heat until the mixture is hot but not boiling.
• In a small mixing bowl, whisk the egg yolks and sugar together until the sugar is dissolved. Then take 1/2 cup of the hot milk mixture and slowly whisk it into the egg yolks while stirring continuously with the other hand. (This process is called tempering the egg. You have to stir constantly and pour the hot milk in slowly, or you'll get scrambled eggs.)
• Turn the burner heat to low. Then slowly add the egg and milk mixture to the rest of the hot milk and keep stirring continuously to prevent the egg from cooking. Let the eggnog cook for a couple of minutes over low heat. It will start to thicken a little.
• Remove from the heat and let the eggnog cool. Stir in the bourbon.

Serving

• Pour the eggnog into glasses and sprinkle some nutmeg and cinnamon for garnish.