In the United States, the traditional Christmas drink made with milk and nutmeg is eggnog.
Eggnog is a rich, sweet dairy drink traditionally prepared with milk or cream, sugar, beaten eggs and spices, commonly grated nutmeg. Brandy, rum, bourbon, whiskey or other spirits may be added, but commercial and homemade versions can also be alcohol-free. The eggs give traditional eggnog its characteristic thick, creamy and frothy texture.
The drink probably developed from older European milk punches and posset, a medieval beverage made with hot milk curdled by wine or ale and flavoured with spices. It crossed the Atlantic in the 18th century, where plentiful dairy products and relatively inexpensive Caribbean rum helped it become popular in the American colonies. After the American Revolution, domestic whiskey and eventually bourbon became common substitutes for rum.
The word eggnog was first printed in the United States in 1788, although an earlier poem mentioning “egg-nogg” dates to 1775. Eggnog is associated with the Christmas season rather than being a uniquely American invention. Mulled wine, apple cider and hot chocolate are also seasonal drinks, but they do not define this milk-and-egg beverage.