When it comes to our old fashioneds, we tend to be dogmatic. There is one way, the pre-Prohibition way. Bourbon, bitters, a hint of sugar, a suggestion of ice. No soda water. No juice. Certainly never fruit.

Then we encountered orgeat and  were forced to acknowledge—if begrudgingly—how wonderfully the deep caramel flavors of our favorite cocktail benefited from the rich almond-orange infused syrup.

Orgeat (pronounced OR-zsa) was one of the first flavored syrups used in cocktails. It showed up in the U.S. around the mid-19th century and eventually became a cornerstone ingredient of the mai tai.

It began in Europe as a barley-­based drink a couple centuries earlier, one of many non-alcoholic “tonics” of that era. But variations of sweet almond-­infused drinks can be found around the world and as early as Roman times.

Today, most orgeat is made by infusing sugar syrup with almonds, both sweet and bitter varieties, as well as rose or orange water. The result is a viscous, sometimes cloudy liquid with a floral-marzipan taste and aroma.

The internet abounds with recipes for making orgeat, and we tried a few, using toasted almonds—ground, slivered and whole. Though easy enough to make—steep the almonds in simple syrup—the results were lackluster. Almondy, yes. But also tedious and time-consuming to make.

So we tested a variety of commercial orgeat and found BG Reynolds Original Orgeat Tropical Syrup to have the cleanest, most evocative flavor. If you buy orgeat, make sure it lists almonds in the ingredients; some brands fake the flavor with extracts.

Though we generally resist any adulterations to the classic old fashioned, orgeat was so alluring, we gave it a try. Substituting it for the sugar gave the drink nutty, lightly fruity flavors that paired perfectly with the bourbon and bitters. 

Classic old fashioneds are made with angostura bitters, but we liked the way orange bitters accented the almond flavor of the orgeat. We liked Woodford Reserve Orange Bitters best, but the more widely available Fee Brothers West Indian Orange Bitters were also good.