In the eighth and final episode of the first season of the 2015 BBC costume drama Poldark, the central character’s sniveling wimp of a first cousin, Francis Poldark, sits at the head of the dining table in his ancestral home. He is unaware that he is showing the first symptoms of “putrid throat.” He instructs his wife: “My throat’s afire. Get Mrs. Tab to fetch me a posset.” His wife responds that the servants are all sick.

The series takes place at the end of the eighteenth century. It begins with the central character, Ross Poldark, a Captain in His Majesty’s Army in America, sitting around a campfire with a small number of fellow soldiers. The group is ambushed by a similar-sized group of colonial soldiers and militiamen, and Captain Poldark is injured. The date is 1781, the year the British suspended fighting in the American Colonies. Two years later, Poldark returns to his native Cornwall. Between Ross Poldark’s return and Francis Poldark’s utterance, a few more years have past.

It was a period where possets were considered both medicinal and refreshing. It was not uncommon for cookbooks to present multiple recipes for possets. Hannah Glasse’s The Art of Cookery Made Plain and Easy of 1747 lists three recipes: “To make an excellent Sack Posset”, To make another Sack Posset”, and “Or make it thus”. John Nott’s The Cook's and Confectioner's Dictionary; or, The Accomplish'd Housewife's Companion of 1723 lists ten recipes: “To Make a Barley Posset”, “To make a Posset”, “Another Way”, “Another Way”, “Another Way”, “To make a French Posset”, “To make a Posset the Earl of Arundel’s Way”, “To make a Covent-Garden Posset”, “To make a Sack-posset”, and “Another Way without Milk or Cream”.

Although Nott has a recipe for a French Posset, I have not found a recipe for one in a French cookbook. Abel Boyer’s Dictionnaire Royal François et Anglois of 1702 provides a definition for posset: Certain Breuvage à l’Angloise, dont le grand usage est par rapport à la Médecine (A certain English beverage, primarily used as a medicine)—but does not provide a French term for the drink. He provides a recipe for a plain posset consisting of just milk and ale as well as two sack-posset recipes. Possets were also popular in the American Colonies. Martha Washington’s family cookbooks contain two posset recipes.

Posset recipes continue to regularly show up in English cookbooks, and the occasional American cookbook, until the 1840s. From that point, the recipes become scarce. The British book Domestic Economy and Cookery for Rich and Poor from 1827 has a curious recipe for “The Pope’s Posset” that consists of mixing three-fourths pound of pounded and boiled almonds with a pound of sweetened sherry. Cassell’s Dictionary of Cookery from 1883, and continuing in later editions, has all the traditional possets plus a few seemingly unique versions including a cornflour (cornstarch) posset and a sack posset claiming to be Sir Walter Raleigh’s personal recipe. The newest British recipe seems to be from E.E. Mann’s Liverpool School of Cookery from 1900. The recipe is for a treacle posset—no alcohol in sight—just milk and treacle. Fannie Farmer provides an Ale Posset in her 1904 Chafing Dish Possibilities. To the recipe she adds: “This is a popular English drink on a cold winter’s night, and is accompanied with toasted crackers and cheese”.

Armed with a healthy dose of confidence and Hannah Glasse’s recipe  “To make an excellent Sack Posset”, I headed downstairs to my kitchen. As is my normal modus operandi, I simplified the recipe down to what I thought were it fundamental elements and reduced the quantities to yield only four small glasses. As my preparation looked like it was about to be completed, the whole mass instantly curdled. I tasted the results and judged them worthwhile to try again. Which I did. And did. And did once again. After my fifth attempt I decided some further thinking was in order. I had modified time, temperature, order of adding ingredients, method of stirring, and whether I was wearing shoes or not. The results still curdled.

For some reason, I decided to look up the word posset in the Oxford Dictionary of English. The definition there was “[historical] a drink made of hot milk curdled with ale, wine, or other alcohol and typically flavoured with spices.” The Oxford English Dictionary said “A drink composed of hot milk curdled with ale, wine, or other liquor, often with sugar, spices, or other ingredients; formerly much used as a delicacy, and as a remedy for colds or other affections.” Hmmm. Both used the word “curdled.” Maybe my goal was misplaced? Definitely not. The curled stuff may have been okay for the colonists, but I don’t like curds in my drink.

As I looked over the group of sack-posset recipes, I decided that the common denominator—if one can apply a mathematical term to an 18th-century drink—was that these preparations all contained the elements of custard. If I make a custard sauce, what common recipe am I actually making? Crème anglaise! What would happen if I made a simple custard sauce and spiked it? So that’s what I did. Who’s to say it’s not a posset?