It's purported to come from the original Fanny Farmer Cookbook. Beat yolks until very light with 1 cup sugar, and salt. Combine and stir until thoroughly blended. Add cream, then milk, then Bourbon. Store in a cold cellar for a week.
Notes Serve with freshly-grated nutmeg.
The egg nog should be ladled from the bottom of the bowl, and never stirred, in order to maintain its layered quality. An alternate method, preferred by some, is to make a creamy, non-layered egg nog by stirring gently every day.