Coosie (or Cocinero)

The camp cook was often called the “cocinero” (Spanish for “male cook”), or simply “coosie” for short.
   
   
Tex-Mex Dictionary
COCINERO (ko-SEE-nair-o)
Male cook. In early pioneer days, the ‘chuck wagon’ on the trail drives was generally an aging cowboy who was the highest paid worker on the drive. In Tex-Mex history, he was referred to as the “cocinero”, especially when of Spanish descent.
   
Cowboy Terms
COCINERO:  Spanish term for male cook or chuck wagon cook.
CHUCK WAGON COOK:  also sometimes called “coosie”, or “cookie.”   
 
Google Books
Cowboy Lingo
by Ramon F. Adams
New York: Houghton Mifflin Books
2000
1936 (original copyright)
Pg. 146:
The cook also had his slang titles, such as “biscuit-roller,” “biscuit-shooter,” “sour-dough,” “dough-roller,” “dough-wrangler,” “sheffi,” “dinero,” “cookie,” “Sallie,” “old woman,” “belly-cheater,” “coosie”—a corruption of the Spanish word cocinero meaning cook—and many others.
 
(Historical Dictionary of American Slang)
cocinero n. [

a cook
1843-45 TJ Green Tex. Exped. 258: Presiding as chief cocinero (cook).
(...)
coosie n. [alter. & abbr. of COCINERO] West.
a cook on a ranch or a cattle drive.
1903 A Adams Log of Cowboy 157 [ref to 1882]: How soon will supper be ready, cusi?
1933 American Speech (Feb.) 27: Coosey. Variation of cocinera.
1933 J.V. Allen Cowboy Lore 60: Coosie, Cook—from the Spanish word cocinero.
 
10 April 1964, Long Beach (CA) Independent, pg. B10, col. 1:
JOHN GAVIN, television’s “Destry,” has compiled a list of names cowboys used to call range cooks. The list follows:
 
Bean master, belly cheater, biscuit roller, biscuit shooter, cocinero, cookie, cook’s louse, coosie, dinero, dough-belly, dough-boxer, dough-puncher, dough-roller, dough-wrangler, flunky, greasy belly, grub spoiler, grub worm, old woman, potbooks, pot rustler, Sallie, sheffi, sop and ‘taters, sourdough and swamper.
 
Gavin has another list of names for range cooks, but I couldn’t print it.
   
10 July 1968, New Mexican (Santa Fe, NM), “Spanish, French, Indian, English—All in Cowboy Lingo,” pg. 4:
Cocinero (coy-the-nay-roh)
Cook. (Sp.)
Coosie
Cook. Shortened from cocinero by the cowboy.