Oh, man...there are so many, but I'll list the first 5 that come to mind!
1) On our last trip I discovered the Butterfinger cupcake at Starring Rolls (better than the red velvet in my opinion)
2) Kaki gori in Japan
3) Chili cheese fries from Pecos Bill's
4) School bread in Norway
5) Mickey bar (you can't go wrong with this one)