The Moroccan fermented butter traditionally flavored with herbs is called smen.
Smen is a preserved, clarified butter made by salting butter and allowing it to mature over time. Some Moroccan preparations add herbs, such as oregano, during the aging process. The result has a strong, savory aroma that can resemble aged cheese and is used sparingly in cooking.
Because much of the water and milk solids are removed or transformed during preparation, smen can be stored for extended periods. It may be added to couscous, tagines, soups, or other dishes to provide depth rather than used like ordinary table butter.
Smen is sometimes confused with ghee. Both are clarified butter products, but smen is salted and fermented or aged, giving it a more pronounced flavor. Amlou is different again: it is a Moroccan spread made from almonds, argan oil, and honey.