If you've got a long-ish layover, would recommend a train into the city (about 15 minutes) and then heading to "De Kaaskamer." This is (in my, and others' opinion) the best cheese shop in Amsterdam. Once you get to Amsterdam Centraal, it's about a 15-20 minute walk (or, you could take a taxi).

The store is located in "De Negen Straatjes" (or "9 Streets") area at Runstraat 7, between the Kaisersgracht and Prinsengracht canals (closer to the Kaisergracht). If you go, one of my favorites is a cheese called Stolwijker (pronounced Stole-viker). They have a young and an old. I'm partial to the old, but the young is really nice as well. Highly recommend the place if you get a chance. Enjoy!
http://www.kaaskamer.nl/?l=en