Sfincione is referred to as thick Sicilian "pizza" but it is actually more precisely a focaccia that is topped with tomatoes, onions, a few anchovies and perhaps grated Casciocavallo cheese, seasoned with a dash of oregano. Outside Italy, the term "Sicilian pizza" is used to describe all kinds of things, but until the 1860s Sfincione which is loosely translated as "thick sponge" was the kind of "pizza" often consumed in Sicily, especially in the western part of the island. Sfincione has a spongy crust up to two (2) centimetres or about an an inch thick, hence, Sfincione is more like bread than pizza which in Italy has usually a thin crust. Sfincione is a local form of "pizza" in Sicily prepared on a thick bread and which is more likely found in a Bakery than in a Pizzeria. Sfincione is good as a snack or appetizer. Sfincione has been made only since the seventeenth century. The most important ingredient, the tomato, is South American in origin and has only been cultivated in Sicily since the sixteenth century. There is a story that Sfincione have been invented by some cloistered nuns, but nobody knows for sure if this story is real. Although the tomatoes are essential in making Sfincione, its real flavor comes from the onions sautéed in olive oil before baking. Sfincione is regarded and listed as one of the street foods of Sicily and it is made or sold by a Sfinciunaro. Street vendors sell Sfincione at Palermo's open-air markets, but some of the best is made by bakeries around Palermo. Traditionally, Sfincione is served on Christmas Eve, New Year's Eve and Good Friday. To prepare Sfincione, only virgin olive oil must be used in the dough and topping and it is baked in a square tray and cut into square or rectangular pieces before serving, unlike the traditional Italian circular pizza.