On progression servers, these can typically be found on "Baking Supplies" vendors. Here's a few that I've confirmed in the past couple of days:
Teria O'Danos Halas
a goblin merchant RunnyEye
a clockwork baker Ak'Anon p885, n300
.... and likely so-on. If someone can give me a list of all Baking Vendors, then I can check them all out/off if it's helpful.
Cheers,
Ashwith