Heat the half-and half-in a saucepan until warm; set aside.

Whisk the egg yolks with the 1/2 cup (99 g) sugar and salt in a medium-sized saucepan until smooth and lightened in color. Slowly whisk in the warm half and half to temper the eggs, so as not to scramble them.

Whisk the custard mixture over low-medium heat - do not let it boil - until it registers 160°F/71°C on an instant-read thermometer. It should coat the back of a spoon. Remove from heat and cool to room temperature. Whisk in 3 ounces (90 ml) of whiskey and vanilla. Taste and add additional whiskey if desired. Refrigerate in an airtight container until needed. Recipe may be made up to this point 1 day ahead.

Whip egg whites in a clean, grease-free bowl until soft peaks form. Gradually add remaining 1/3 cup (65 g) sugar and beat on high speed until stiff peaks form. Fold into cooled custard. Eggnog is ready to serve. Garnish with freshly grated nutmeg on top right before serving.