Grandma pizza is a distinct thin, rectangular style of pizza attributed to long island, new york. typically topped with cheese and tomato sauce, it is reminiscent of pizzas baked at home by italian housewives who lacked a pizza oven. the pizza is often compared to sicilian pizza. a grandma pizza is typically rectangular, with the cheese placed before the tomato sauce, baked in a sheet pan in a home oven, and cut into small squares.

Source: Wikipedia