In a large bowl, beat the egg yolks with a handheld electric mixer on medium speed until they lighten in color. Gradually add 1/3 cup sugar and continue to beat on medium speed until it is completely dissolved. Add the milk, cream, bourbon, cognac, and nutmeg, stirring to combine.

Place the egg whites in the bowl of a stand mixer and beat to form soft peaks on medium-high speed. With the mixer still running, gradually add the remaining tablespoon of sugar and beat until stiff peaks form.

Whisk the egg whites into the egg yolk mixture. Chill for 2 hours and serve.