Archaeologists say they have found traces of 2,500-year-old chocolate on a plate in the Yucatan peninsula, the first time they have found ancient chocolate residue on a plate rather than a cup, suggesting it may have been used as a condiment or sauce with solid food.

Experts have long thought cacao beans and pods were mainly used in pre-Hispanic cultures as a beverage, made either by crushing the beans and mixing them with liquids or fermenting the pulp that surrounds the beans in the pod. Such a drink was believed to have been reserved for the elite. But the discovery announced this week by Mexico’s National Institute of Anthropology and History expands the envelope of how chocolate may have been used in ancient Mexico.