Chicago has deep dish pizza, New York has its thin-crust slices, and Philly has tomato pie. Before you imagine a flaky pie crust filled with tomato paste or something else outlandish, know that tomato pie is simply a delicious and unique square-shaped pizza pie, first introduced to Philadelphia by Italian immigrants.

During the 19th and 20th centuries, political instability in Italy climbed upward, and more Italians migrated to the United States, landing in Philadelphia, where they relied on tomato pie to fill their bellies without breaking the bank. The pie is based on the dish “Sfincione Palermitano,” meaning “the thick sponge of Palermo.”

Tomato pie is often served at room temperature, and consists of a fluffy focaccia bread-like base topped with tomatoes; the only cheese, if any, is a sprinkle of parmesan. As “Sfincione Palermitano,” suggests, the dish hails from Palermo, where tomatoes and olives were more common than dairy; thus, the lack of cheese.