April 5th: National Deep Dish Pizza Day - Also known as Chicago-style pizza today we celebrate National Deep Dish Pizza Day. Deep dish pizza was created in Chicago in 1943 by Pizzeria Uno’s founder Ike Sewell. Deep dish pizza has a buttery cornmeal crust than can be as tall as 3 inches on the sides. That way the crust acts like a bowl to hold in all the yummy ingredients. The pizza is made upside down so the cheese goes in first, then toppings, then sauce.