Entry in progress—B.P.
 
Wikipedia: Sicilian pizza
Sicilian pizza, also known as Sfincione (or Sfinciuni in Sicilian language) is a variety of pizza with ingredients sometimes incorporated into the dough, instead of just placed on top. This variety of pizza originates from Palermo, Sicily. An authentic recipe does not use mozzarella cheese, often adding small chunks of pecorino cheese and bits of anchovies.

However, in the United States, a Sicilian pizza is a square pie with dough over an inch thick. This pizza is very popular, primarily in the New York area, where is is often called square. It is typically served in an aluminum baking sheet.

A particular variety originated from Messina, Sicily, which can be both considered a Sicilian Pizza or a focaccia, it’s the focaccia alla messinese made with endive and anchovy.
   
22 March 1948, Chicago (IL) Daily Tribune, Mary Meade food column, pg. A7:
A good many of my readers are going to want this new cook book: “The Art of Italian Cooking,” by Maria Lo Pinto ($2.75, Doubleday and Co., New York). (...) Among the 200 recipes in this book are such dishes as rabit—hunter’s style, brandied duck, Sicilian tomato pie (pizza Siciliana).
 
21 July 1953, Chicago (IL) Daily Tribune, Mary Meade food column. pg. A3:
“I also use the creamed cottage cheese for pizza Sicilian style, when I can’t get ricotta. I roll out the pizza dough, not too thin, spread with sauteed onions, a thin layer of the cheese, then seasoned crushed canned tomatoes, a thin sprinkling of grated Parmesan or Romano cheese, oregano, and a few drops of oil in which a small clove of farlic has been crushed, and bake it. This is a rich and filling pizza, and with a tossed vegetable salad, it’s a complete meal.”
   
1 October 1953, Wisconsin State Journal (Madison, WI), “Pizza Ranks as Favorite Dish in U.S.,” section 2, pg. 3, col. 2:
Although the Neopolitan-type pizza is sold in 90 per cent of American pizzerias there is also a Sicilian pizza, slightly thicker, more breadlike and baked in a pan.
 
22 December 1955, Chicago (IL) Daily Herald, Pg. 69?, col. 1:
PIZZA
AT
MILLIE’S
Green St. at York Rd. in Bensenville
“Try Our Sicilian Pizza”
   
2 December 1960, Van Nuys (CA) News, ‘Americans Flip For Pizza Snack,” pg. 2B, col. 6:
Sicilians frequently counter the claim that pizza originated in Naples. The islanders take credit for the taste treat, also stressing the fact that Sicilian pizza is different in that its dough it nearly an inch thick—it’s more of a cake than a pie.
   
21 January 1965, Los Angeles (CA) Times, pg. OC4 ad:
Add zest to your meals, give the family a special treat, visit the brand new, so unusual bakery FRANK PANZARELLA just opened in the Magnolia Center, Magnolia & Ball, Anaheim. Mr. Panzarella, a master baker offers Italian, French and Sicilian breads, rolls and pastries. You must try the delightful Sicilian Pizza, different in shape, they’re square, and certain to delight one and all. Open 24 hours a day, all baked each night and ready, warm from the ovens. Free delivery within the area. FRANK’S BAKERY, OR CALL 827-8440.
 
Google Books
29 November 1971, New York magazine, pg. 75, col. 3:
On the positive side, Sbarro’s pizzas are first rate. Try the Sicilian pizza (50 cents a slice).
 
New York (NY) Post (October 7, 2004)
Pg. 88:
The first know (sic) pizzeria in the US opened in New York City in 1905, by Gennaro Lombardi. Lombardi’s is still going strong, on SPring Street.
 
Although Neapolitans were the purists, it’s believed that Bologna was the region that started to use meat—but the Sicilian pizza is not from Sicily at all—it’s an American invention.
     
Google Books
The Everything Pizza Cookbook:
300 Crowd-Pleasing Slices of Heaven!
By Belinda Hulin
Published by Everything Books
2007
Pg. 6:
Sicilian
True Sicilian pizza is a rectangular slab of bread with toppings—which typically do not include cheese—pushed into the dough before baking. The American version is radically different, usually with a thick layer of cheese encasing all the toppings. Sicilian pizza can be found in major metro areas with large Italian-American populations, and homogenized versions occasionally turn up on the menu of pizza chain restaurants. Scranton-style pizza, served at pubs and bakeries in Northeastern Pennsylvania, is a thick, pillowy rectangular crust with a crisp bottom, topped with thick tomato sauce and a thin layer of grated hard cheeses. One can argue that pizza (Pg. 7—ed.) variations like French-bread curst pizza and focaccia pizza pay homage to the original Sicilian pizzas.

General Chowhounding Topics - Chowhound
What is Sicilian pizza like?
I must admit my ignorance here…What is Sicilian pizza like? Like New York pizza?
jinet12 Mar 25, 2007 08:43AM
 
sicilian pies are rectangular with a doughier thicker crust. but not full of butter like chicago style. ny pizza is very thin soft crust that you can fold.
hotoynoodle Mar 25, 2007 11:54AM
 
re: hotoynoodle NY pizza is thin crust, but not really soft. It cracks a bit when you fold it.
 
NY Sicilian is rectangular slabs 3"x5” with a crust around an inch thick. The amount of sauce is greater and the cheese is very thick.
JMF Mar 25, 2007 01:47PM
 
This image is a typical NY square slice (aka a ‘Sicilian’ in MOST boroughs and beyond). A lot of people in Brooklyn might debate this and chime in with their ‘Grandma’ slice stories etc., but in the meantime, here’s an image for you to gaze at ... http://academianovibelgii.org/Miscellanea/IMG_BrooklynSicPizza1.jpg
 
Then, there’s the Sicilian sfincione (scroll, and check out these pics) ... http://www.palermoweb.com/panormus/gastronomia/sfincione.htm
 
I’ll let others chime in with the specifics of each. They are very different in taste, texture, and toppings…but, both are considered Sicilian pizza, and both are rather thick.
 

I couldn’t leave this out. This is very “Brooklyn” and some will argue that THIS is truly Sicilian pizza. Look—-> http://www.flickr.com/photos/laurea/2...
Cheese Boy Mar 25, 2007 02:10PM