2 Answers

A posset (also spelled poshote, poshotte) was a British hot drink of milk curdled with wine or ale, often spiced, which was popular from medieval times to the 19th century. The word is mainly used nowadays for a related dessert similar to syllabub.
To make the drink, milk was heated to a boil, then mixed with wine or ale, which curdled it, and the mixture was usually spiced.[2]
It was considered a specific remedy for some minor illnesses, such as a cold, and a general remedy for others, as even today people drink hot milk to help them get to sleep.

http://en.wikipedia.org/wiki/Posset

pos·set/?päs?t/
Noun:
A drink made of hot milk curdled with ale, wine, or other alcoholic liquor and typically flavored with spices