Galette des rois is a cake served in France to celebrate the arrival of the Three Wise Men on January 6th. In the traditional galette des rois, a tiny object or a small toy is hidden in the dough and whoever gets the slice containing it, they become a queen or a king for the day. The surprise added in the cake originally was a broad bean.
The correct pronunciation of Galette des rois is gah-LEHT deh roo-AH. The stress is on the capital letters.