In a large bowl, beat the egg yolks until they lighten in color. Gradually add the 1/3 cup sugar and continue to beat until it is completely dissolved. Set aside.
In a saucepan, combine the milk, heavy cream, and nutmeg. Bring to a boil over medium heat, stirring occasionally.
Remove the milk mixture from the heat and gradually temper the hot mixture into the egg and sugar mixture.
Return everything to the pot and cook until the mixture reaches 160°F (71°C).
Remove from the heat, stir in the bourbon or rum if desired, and pour into a medium mixing bowl. Set in the refrigerator to chill.
In a medium bowl, beat the egg whites to soft peaks. With the mixer still running, gradually add the 1 tablespoon of sugar and beat until stiff peaks form.
Whisk the egg whites into the chilled mixture.
Serve with a sprinkle of nutmeg on top.