Whisk the egg yolks and sugar together in a medium bowl until light and creamy. Set aside.

In a saucepan over medium-high heat, combine the cream and milk. Stir often until mixture reaches a bare simmer. Remove from heat.

Slowly whisk the milk mixture into the bowl of creamy egg and sugar mixture little by little. DO NOT ADD IT ALL AT ONCE. Continue to whisk until all the milk is whisked in.

Pour the mixture back into the saucepan and cook on medium heat, stirring constantly  until the mixture thickens to your desired consistency .

Remove from heat and stir in the vanilla and nutmeg.

Pour the mixture into an airtight container.

Chill the eggnog in the refrigerator for at least two hours.

Stir completely before serving.

Pour into glasses.

Serve with a sprinkle of cinnamon or nutmeg, and fresh whipped cream, if desired.