“LOOK!” I was sitting in the airport in Brussels, waiting for a flight back to the States while listening to an American gate attendant bungle a seemingly endless list of Flemish names into a microphone. My boyfriend, who had wandered off to buy a bottle of water, came bounding back to the gate with a giddy smile on his face. He was clutching one of those vacuum-sealed duty free bags. But instead of holding a bottle of booze, it held a tiny, plum-sized, pale blue container. It would be instantly recognizable to anyone who spent their childhood in Belgium, as indeed he had: sirop de Liège.

“Préparé avec 400 g de fruits pour 100 g,” boasts the label. Made with 400 grams of fruit per 100 grams of syrup, sirop de Liège (Luikse Siroop in Flemish) is a sticky-sweet paste made from the evaporated and reduced juices of pears, apples, and dates. What these three fruits have in common is that they all contain a ridiculous amount of the natural thickener pectin, which makes sirop de Liège a sort of stickier, sweeter, thicker variation of apple butter.

So that covers the sirop part. The Liège refers to the Liège region, located in the Walloon (French-speaking) part of Belgium, about an hour southeast of Brussels. Despite the name, the most famous producer of sirop de Liège—the one responsible for those iconic baby-blue tubs—is actually located about half an hour away from the city of Liège in Aubel. 

It’s a treat enjoyed across the country. Although it’s typically enjoyed for breakfast—more on that in a second—sirop de Liège is actually quite versatile. Should you encounter a dish, usually meatballs or rabbit, prepared “à la Liégeoise,” that means it’s dressed in a sauce made from sirop de Liège. The syrup is also used to prepare lacquemant waffles, a specialty of (surprise) Liège in which two thin wafers are glued together and then laquered with syrup. Unlike American waffles, these are an afternoon delicacy, and are a common treat at the Liège Fair, which takes place each October. 

But sirop de Liège’s first true love is breakfast. Indeed, having just spent two weeks traveling through Belgium, the small blue pots of syrup were on every breakfast spread I encountered. A Gent innkeeper sighed dreamily one morning as she talked about the decade she spent living in Paris, where the only Belgian food she missed was sirop de Liège. And my boyfriend gleefully slathered it over every piece of bread he encountered.

“Sur vos tartines,” recommends the label. “Op uw boterham.” For your toast. Sometimes with fresh cheese, sometimes with butter, sometimes with neither. But always with a syrup that’s worth traveling halfway around the world for.