Step 1

Place egg yolks in a saucepan. Whisk in sugar until well blended and creamy. Add milk and cream; whisk until blended. Place pan over medium heat; whisk frequently until mixture reaches a temperature of between 170 to 180 degrees F (75 to 80 degrees C) using an instant-read thermometer. Remove from heat. Stir in nutmeg and whiskey.

Step 2

Chill pan in cold water until cool. Transfer mixture to a container (a large pitcher is ideal). Cover and refrigerate until thoroughly chilled, 2 to 3 hours.

Step 3

Place egg whites in a bowl and whisk until soft peaks form. Add sugar and continue whisking until egg whites hold a firmer peak. Whisk egg whites into custard base until thoroughly blended. Refrigerate until chilled, about 30 minutes.

Step 4

Whisk eggnog again just before serving and between each pour to ensure even distribution of the egg whites which tend to float to the top. Serve with a dusting of nutmeg.