The word covers a family of flat things. The free-form fruit galette is a single crust laid flat, filled with sliced seasonal fruit such as apples, berries or stone fruit, and folded over at the edges so the center stays open. In Brittany the same word names a large buckwheat pancake, usually savory; the galette complète carries ham, grated Emmental and an egg.
The best-known galette is the galette des rois, eaten in France for Epiphany on 6 January. It is usually puff pastry filled with frangipane, or in some regions a brioche ring with candied fruit. A small figure called the fève is baked inside, and whoever finds it wears the crown supplied with the cake.
The custom of choosing a king by a token in a cake is often traced to the Roman Saturnalia. That link is repeated widely but rests on secondary accounts. Connexion France dates a related custom, in which the finder of the fève bought drinks for the table to cries of “Le roy boit!”, to the fourteenth century.