“One Chatham Square” was old New York City restaurant slang for “beef stew.” The term was first cited in an 1888 newspaper, reporting on the strange orders at a restaurant on Ann Street. The establishments in Chatham Square in the 1880s were probably known for serving beef stew.
 
The “One Chatham Square” term for beef stew has only one printed citation and is of historical interest today.
 
     
Wikipedia: Chatham Square
Chatham Square is a major intersection in Chinatown, Manhattan, New York City. The square lies at the confluence of eight streets: the Bowery, Doyers Street, East Broadway, St. James Place, Mott Street, Oliver Street, Worth Street and Park Row. The small park in the center of the square is known as Kimlau Square and Lin Ze Xu Square.
 
History
Chatham Square was named for William Pitt, 1st Earl of Chatham and Prime Minister of Great Britain before the American Revolution. Pitt Street in the Lower East Side is also named for him, and Park Row was once Chatham Street.
 
Up until about 1820, the square was used as a large open air market for goods and livestock, mainly horses. By the mid-19th century, it became a center for tattoo parlors, flophouses and saloons, as a seedy section of the old Five Points neighborhood. In the 20th century, after The Great Depression and Prohibition, the area was reformed.
 
Hudson River Valley Heritage Historical Newspapers (NY)
24 March 1888, The Rockland County Journal (NY), “Waiters’ Queer Orders,” pg. 6, col. 1: 
A NEWS reporter went into a restaurant on Ann street yesterday and after having given his order to the waiter asked him what was the meaning of the jargon waiters usually shriek at the cook.
(...)
Ask for a beef stew and your order will be twisted into “One Chatham square.”
(...)
—N. Y. News.