What dialect is "moogoo gaipan" (蘑菇雞片)?

There’s a dish known as moogoo (or mugu) gaipan, which is 蘑菇雞片, mogu jipian in Mandarin.

Since it’s supposed to be a Cantonese dish, but the Cantonese pronunciation should be mogu gaipin, I’m wondering how it came to be pronounced the way it is in English. Is it just a bastardization, or is it from an obscure dialect?

Bastardisation if you ask me.

Wiktionary suggests that the etymology is Taishanese:

moo goo gai pan - Wiktionary, the free dictionary

This is the etymology from the entry of the old Bartleby.com version of the American Heritage Dictionary (saved in the Internet Archive):

moo goo gai pan. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

But this is the etymology from the entry of the current online version of that dictionary:

American Heritage Dictionary Entry: moo goo gai pan

I favor Wiktionary’s opinion, but I may be biased, because I’m from Louisiana:

from “Researching Chinese American History in New Orleans 紐奧良華僑歷史研究,” on Facebook