Well, there’s a good chance it comes from glands of the beaver.....beaver butt glands (or close). Glad you had your creme brule before I shared this little bit of trivia with you! I just wonder how this was discovered lolo!
https://www.allrecipes.com/article/vanilla-beaver-castoreum/

NO COMMENT!!
But I did brush my teeth extra long last night.
Pass this information on to the POTUS46 sniffer.
Beaver Butts Emit Goo Used for Vanilla Flavoring
The FDA regards castoreum as “natural flavoring.”
https://www.nationalgeographic.com/animals/article/beaver-butt-goo-vanilla-flavoring
EXCERPT:
Just in time for holiday cookie season, we’ve discovered that the vanilla flavoring in your baked goods and candy could come from the anal excretions of beavers.
Beaver butts secrete a goo called castoreum, which the animals use to mark their territory. The U.S. Food and Drug Administration lists castoreum as a “generally regarded as safe” additive, and manufacturers have been using it extensively in perfumes and foods for at least 80 years, according to a 2007 study in the International Journal of Toxicology.
“I lift up the animal’s tail,” said Joanne Crawford, a wildlife ecologist at Southern Illinois University, “and I’m like, ‘Get down there, and stick your nose near its bum.’”
“People think I’m nuts,” she added. “I tell them, ‘Oh, but it’s beavers; it smells really good.’”