How to Make It
Separate egg yolks and egg whites* into two large bowls. With a wooden spoon, beat egg yolks together. Then, a little at a time and very slowly, stir bourbon into the egg yolks, making sure to completely incorporate the bourbon before adding more. Don’t rush this process; it’s the gradual mixing in of the alcohol that thickens it and will yield the best light and custardy texture to the finished eggnog when it’s done. When all the bourbon has been incorporated, keep stirring the mixture slowly.
Next, beat egg whites at high speed until soft peaks form. (If you use a stand mixer, this step can be managed while you are stirring bourbon into the egg yolk mixture.) Reduce mixer speed to medium and gradually add sugar, then increase speed to high until egg whites are stiff.
Fold one-fourth of the beaten egg whites into the bourbon-egg mixture until incorporated. Then fold in half of the remaining beaten egg whites, and then fold in the rest, gently. You want the beaten egg whites to be mixed in with the bourbon-egg mixture, but also to retain the airy fluffiness of the meringue.
Beat heavy cream until peaks form; don’t overbeat.
Spoon eggnog immediately into glasses or silver goblets, and top with a large spoonful of whipped cream. Grate fresh nutmeg over the cream and serve with a spoon.