Recipe adopted from Mel's Kitchen Cafe. [Recipe makes 3 1/3 cups of eggnog, 2 to 4 servings].
6 large egg yolks, room temperature
3 1/2 ounces (~1/2 cup) sugar
1 cup heavy cream
2 cups whole milk
Pinch of kosher salt
1/4 teaspoon vanilla extract
1 1/2 teaspoons freshly grated nutmeg, plus additional for garnish
Create an ice bath by combining ice cubes and cold water in a large metal bowl. Reserve.
In a medium bowl, whisk the egg yolks with the sugar until the egg yolks turn pale yellow in color and the consistency is at the ribbon stage. In a medium saucepan, whisk together the cream, milk, and salt. Bring the liquids to a light simmer. While whisking with one hand, add a few tablespoons of the simmering milk to the egg mixture. Add an additional 1/4 cup of milk to the eggs while whisking. Continue incorporating the milk into the eggs, adding a little more each time. Once the eggs are tempered and the two mixtures are fully incorporated, transfer back to the saucepan and cook over medium heat until a temperature of 160° F is met. [Side note: For those of you without a cooking thermometer, this would be the type of situation where it is worth having one. Although not recommended due to food safety reasons, the additional cooking time needed to reach 160° F will only take a minute or two if you choose not to use a thermometer].
Remove from the heat and pass the eggnog through a fine mesh strainer and into a clean bowl. Stir in the vanilla and nutmeg. Transfer the bowl to your ice bath and cool within a safe amount of time, stirring every 15 minutes. Once cooled, transfer the eggnog to a sealed container and refrigerate overnight to let all the flavors come together.
To serve, pour into individual glasses and garnish with additional freshly grated nutmeg.