The cobblestone streets just north of the gilded Grand Place in central Brussels hum with tourists darting in and out of shops on twisting alleyways that offer hints of their gastronomic past—the medieval markets selling butter or herbs, the butchers, fishmongers and more.

It was on Butter Street that bakery Maison Dandoy became famous for its speculoos, a crispy, spiced buttery cookie enjoyed year-round. Few bakeries are as closely linked to a single baked good as Maison Dandoy is to speculoos, where 3-foot-long versions of the stamped cookie are a popular holiday gift. “We eat a lot of cookies,” says Antoine Helson, a member of the seventh generation running Maison Dandoy.

A converted pharmacy, the store is lined with apothecary boxes displaying all manner of cookies. But the speculoos are No. 1 for a reason. The crispy, light biscuits are powerfully aromatic of cinnamon and clove, as well as a molasses flavor that comes from a dark brown sugar made from beets. Helson walks me through the process, which begins with creaming butter with spices and some of the sugar. More sugar, then flour and baking soda before kneading and pressing into a floured mold.

We loved the cookies’ spice and light texture, but when we tried recreating them at Milk Street, we were left with a too-crunchy cookie that lacked flavor. The solution lay in substitutions for two Belgian-made ingredients—the dark beet sugar and the flour, which is softer and more tender than U.S. brands. Cake flour, plus slightly more butter, gave us the lighter texture we wanted. And a couple tablespoons of dark corn syrup in addition to light brown sugar replicated the delicate flavor of the beet sugar.

The resulting cookie was delightfully crisp and blooming with spice—not to mention easier on the teeth.