“Holy guacamole!”; “Holy cannoli!”

“Holy guacamole!” (cited in print since at least 1968) and “Holy cannoli!” (cited in print since at least 1982) are two popular food exclamations.  “Holy guacamole!” was popularized by the television show Batman (1966-68).
 
“Holy guacamole!” was probably influenced by the older “Hol(e)y mol(e)y!” (cited in print since at least 1892). The origin of this exclamation of surprise is uncertain. “Holey Moley!” was popularized by the 1940s “Captain Marvel” comic books.
 
“Holy mackerel!” is an expression of surprise that has been cited in print since at least 1867. Similar food expressions (some also rhyme with “holy”) include “Holy jalapeño!”, “Holy pepperoni!” and “Holy shiitake!”
   
   

Wiktionary: holy moley
Alternative forms
holy moly!
Etymology

c. 1892
Interjection
holy moley!

1.(idiomatic, dated, humorous or euphemistic) An expression of surprise
Synonyms
. holy cow
. holy mackerel
. holy smoke
 
TV Acres—Catchphrases
“Holy Guacamole, Batman!” - One of the silly exclamations spoken by the Boy Wonder (Burt Ward), a Gotham City crimefighter on the fantasy adventure BATMAN/ABC/1966-68. The following is a list of a few more of his silly syllables: Holy Armadillos!, Holy Chutzpah!, Holy Contributing to the Delinquency of Minors!, Holy Dental Hygiene!, Holy Fate Worse Than Death!, Holy Guadalcanal!, Holy Hieroglyphics!, Holy Hole-In-A-Doughnut!, Holy Human Surfboards!, Holy Hydraulics!, Holy Hypnotism!, Holy Interplanetary Yardstick!, Holy Kilowatts!, Holy Luther Burbank!, Holy Mashed Potatoes!, Holy Molars!, Holy Priceless Collection of Etruscan Snoods!, Holy Purple Cannibals!, Holy Ravioli!, Holy Rising Hemlines!, Holy Trolls and Goblins!, and Holy Uncanny Photographic Mental Processes! Holy Moley!, aren’t you glad that’s over?
 
(Historical Dictionary of American Slang)
moley n. [pop. as a characteristic exclamation of “Captain Marvel,” hero of a series of comic books begun 1940, first written by C.C. Beck, perh. relfecting moly ‘magic herb in Greek mythology’, in allusion to the invocation of mythological figures as a source o the character’s powers; perh. euphem. and rhyming alt. of holy Moses]  In phrase: holy moley (used as an exclamation of surprise).
1949 Capt. Marvel Adventures, in Barrier & Williams Book of Comics 87: Holey Moley! He got away.
1958 Reuss & Legman Songs Mother Never Taught Me(unp.): “Holy Moley,“I cried out.
 
Google Books
Running it off; or, Hard hit
By Nathaniel Gould
London: George Routledge and Sons, Limited
1892
Pg. 217:
“Whew !” he whistled, softly; “that’s curious. Same name as the lady at our place. Suppose he should be her husband. Holy moley, what a game. I’ve made a discovery.”
 
2 April 1935, Oregonian (Portland, OR), pg. 9, col. 3:
HOLEY MOLEY—Editor of “Today” speaks on “Interstate Co-operation in Combating Crime,” KGW, 4:45.
     
2 November 1951, Oakland (CA) Tribune, “Buck O’Rue” comic strip by Dick Huemer, pg. 36, col. 1:
“HOLY MOLEY! I’M DEFENSELESS!”

Google Books
Broadcasting
Volume 74
1968
Pg. 18:
“Holy guacamole,” is more than a catch phrase in a radio campaign. It represents our feelings at Calavo about the recent results of a broadcast campaign introducing frozen guacamole in 11 markets across the country.
(...)
MAN: Do you realize that Calavo is the only one in history to successfully freeze a ready to serve avocado dip?
MAN: Holy guacamole!
   
15 February 1968, Van Nuys (CA) News, pg. 15B, col. 6 photo caption:
HOLY GUACAMOLE—Three-and-a-half year old Daniel Hawson and his grandmother, Mrs. Ruth C. Eads sample dip from Guacamole cart which will be at the Topanga Plaza Shopping Center tomorrow and Saturday.
 
Google Books
Take Five
By D. Keith Mano
Garden City, NY: Doubleday
1982
Pg. 61:
“Holy-cannoli, y’know, I hardly miss them.”
 
3 August 1983, Baltimore (MD) Sun, “Heads up—it’s celebrity tennis” by Laura Charles, pg. B2: 
HOLY CANNOLI: Dashed down to the Italian Festival the other day to take part in ...
 
Google News Archive
7 September 1983, Mid Cities Daily News (Hurst, TX), “Hardcover cookbooks expensive but paperback bargains abound” by Jeanne Lesem (UPI Family Editor), pg. 2B, col. 2:
“Soup Bowl West,” by Marge Mitchell and Joan Sedgwick(Random House, $8.95).
(...)   
Recipes include Unholy Guacamole, Chino Valley Bean Soup and several chilies.

OCLC WorldCat record
Holy cannoli : a farce in two acts
Author: John D Smitherman
Publisher: Venice, FL : Eldridge Pub., ©2000.
Edition/Format:  Book : English
 
OCLC WorldCat record
Holy guacamole!
Author: Nancy Fairbanks
Publisher: New York : Berkley Prime Crime, 2004.
Series: A culinary mystery with recipes
Edition/Format:  Book : Fiction : English : Berkley Prime Crime mass-market ed
Summary: At an opera party in Texas, the artistic director eats some bad guacamole that disagrees with him right to death. A scorned soprano admits to mixing the dish to get back at him for passing her over for her dream role. But Carolyn learns that foul play, not foul food, was the real culprit—and uncovers some unsavory secrets that lead to a full menu of suspects.
 
OCLC WorldCat record
Holy guacamole! : and other scrumptious snacks
Author: Nick Fauchald; Rick Peterson
Publisher: Minneapolis, Minn. : Picture Window Books, ©2008.
 
OCLC WorldCat record
Holy guacamole! New disease crops up in avocados
by L Lochridge
Article
Language: English
Publication: CITRUS AND VEGETABLE MAGAZINE, 73, no. 9, (2009): 21
Database: British Library Serials
Series: Kids dish. 
Edition/Format:  Book : Juvenile audience : English
Summary: Easy snack foods kids can prepare.
Indexed by category, main ingredient, and preparation time, these fun and safe recipes, which use simple directions and everyday ingredients, allow young chefs to easily create foods they’ll love.