Has anyone seen these sold in any Bangkok stores? Had one in a meal at the Kiwi bar once, but not seen them on General sale anywhere.

There are Expat services in Bkk that you might want to try, like these guys:

http://www.buntersfoodsbkk.com/index.html

 

 

Villa stocks them.  Wrapped in cellophane so the crumbs go soggy.  Expensive, too.

 

TOPS occasionally has them in the help-yourself-to-prepared-curries-and-western-food section.

Try making your own... there are lots of good examples on YouTube.