These Meiji chocolate bar puzzles come in different difficulties, too -- as the chocolate flavor gets more bitter (white, to milk, to dark), the piece placement gets harder. Of course, the hardest part would be the test in willpower. It's not easy to play the puzzle after you eat all the pieces, we're sure.
These might stale by the time you import them, but if you'd like some anyway for the novelty they cost 730 JPY (about $7 USD) each at Strapya World, sans shipping. As of posting this, there were only four units in stock, so you might want to get on that quickly if you covet such treats.
We just hope there's not too many zigzags.
[Update: I just found out that the chocolate isn't actually edible! (Hear that? It's the sound of my heart breaking.) Sorry if I got any of your hopes up, too!]