In the bowl of a stand mixer or with a hand mixer, beat egg yolks at medium-high speed until thick and pale yellow.
Slowly add two-thirds of a cup of the powdered sugar (save one-third for later) and beat until fully dissolved.
Add the rum (or other spirits), milk, heavy cream, nutmeg and almond extract and stir to combine.In a separate bowl, beat the egg whites until they maintain soft peaks.
Gradually add the remaining one-third cup of powdered sugar and beat until incorporated and stiff peaks form.
Gently whisk the egg whites into the eggnog mixture.
Chill, and serve in a punch bowl.
Garnish with freshly grated nutmeg sprinkled on top.