n. — Food
burger with bacon and cheese (see Image 1).
Type: 1. Origin — Banquet burger appears to be Canadian in origin. The first known attestation of the term comes from a Windsor Star newspaper advertisment from 1968 for Mady's Big Boy Restaurant (see the 1968 quotation). There is some confusion owing to the fact that the restaurant shares a name with the popular US franchise Big Boy Restaurants. However, Mady's Big Boy restaurant was not a franchisee.
The term is most frequent in Canada according to internet domain searches (see Chart 1).
See also COD-2, s.v. "banquet burger", which is marked "Cdn".
Images:

Image 1: A banquet burger (with onion). Source: Wikimedia Commons. Photo: Celeste Lindell 
Chart 1: Internet Domain Search, 29 Oct. 2013