In Medieval times a popular drink called a posset was a warming concoction of hot milk mixed with hot beer, sherry, etc., sugar and various spices. Excellent for keeping the cold at bay. In 1669 this was the recipe for one type called a sack posset:
“Take three pints of Cream; boil in it a Little Cinnamon, a Nutmeg quartered, and two spoonfuls of grated bread; then beat the yolks of twelve eggs very well with a little cold Cream, and a spoonful of Sack. When your Cream hath boiled about a quarter of an hour, thicken it up with the Eggs, and sweeten it with Sugar; and take a half a pint of Sack and six spoonfuls of Ale, and put into the basin or dish, you intend to make it in, with a little Ambergreece, if you please. Then pour your Cream and Eggs into it, holding your hand as high as conveniently you can, gently stirring in the basin with the spoon as you pour it; so serve it up. If you please you may strew Sugar upon it. You may strew Amberedsugar upon it, as you eat it; or Sugar-beaten with Cinnamon, if you like it.”
By the mid-1760’s, American colonials were drinking what they called eggnog. That recipe has been preserved in The Williamsburg Cookbook and calls for: 1 cup sugar, 1 cup bourbon, 1 cup cognac, ½ teaspoon salt, 3 pints whipping cream and nutmeg. Beat the egg yolks with sugar until thick. Slowly add bourbon and cognac. Chill several hours. Whip egg whites with salt until stiff. Whip cream and add broth to egg yolk mixture. Chill 1 hour. Sprinkle with nutmeg. Note: For thinner eggnog pour 1 cup of milk in with egg yolks.
From The Williamsburg Cookbook
Commentary by Joan Parry Dutton [Colonial Williamsburg Foundation: Williamsburg VA] 1971 (p. 158-159)
An excellent contemporary version can be found at: http://kitchenconfidante.com/coconut-hazelnut-eggnog-recipe