The closest form the the eggnog we know today is from American colonial times where a egg based beverage was mixed with "grog" a term widely used for rum. this "egg-n-grog" eventually became the eggnog that we can now find stocking our refrigerators as soon as the thermometer drops.
Here is a recipe courtesy of Wirtz's Beverages master mixologist Drew Levinson...
Pumpkin Spice Eggnog
1 oz. Spiced Rum (Kilo Kai or Sailor Jerry)
½ oz. Courvoisier Exclusif Cognac (VS or VSOP works)
5 oz. Old Fashioned Eggnog, recipe follows
Dash Ground Pumpkin Spice (or Hiram Walker Pumpkin Spice Liqueur)
Shake ingredients with ice, and strain into a chilled Wine Glass.
Garnish with freshly grated nutmeg on top.
Eggnog can be purchased at the grocery store or if you are feeling ambitious you can make your own fresh version!
Eggnog from scratch
12 jumbo eggs
½ lb. granulated sugar
1 qt. whole milk
1 qt. heavy cream lightly whipped
1 tsp. vanilla extract
½ tsp. cream of tartar
Separate egg yolks from egg whites. Beat yolks in a large bowl. Gradually add sugar. Beat until mixture thickens; stir in milk, & lightly whipped cream. Cover and chill for 3-4 hours. In a separate bowl, beat egg whites with cream of tartar until soft peaks form. Fold whites into chilled mixture.