Real egg nog is a super-treat, with or without rum.
3 eggs, separated
2 tablespoons sugar, or to taste
1/2 teaspoon vanilla extract
3 cups milk or half-and-half
1/2 cup rum (optional), or more if desired
Freshly grated nutmeg to taste
1. Beat the egg yolks with the sugar until well blended. Stir in the vanilla, the milk or half-and-half, and rum if desired.
2. Beat the egg whites and fold them in thoroughly. (You need not be too gentle; they should lighten the drink but not be discernible.) Top with grated nutmeg and serve.