I was once at a Scotch tasting where our host passed around dark chocolate to taste alongside the whisky. He explained that the alcohol would chemically act upon the chocolate to break it apart and the result would be added depth of flavor. This is similar to how adding a splash of water to a whisky can "open it up" and reveal deeper flavors. At the time, I was skeptical that the host's chocolate might be a ruse to cover up a subpar single malt, but damned if he wasn't right about the pairing.
My wife recently bought a bar of fine dark chocolate, and I thought it would be fun to taste a few tiles alongside some single malts and see which pairing I liked best. I tried a variety of whisky styles including Highland Park 12, Glenlivet Nadurra 16, Ardbeg 10, Macallan Cask Strength, and Lagavulin Distiller's Edition.
Here are my impressions:
Highland Park 12: The heather malty flavor of HP 12 does not pair well, and the chocolate drowns the complexity of the whisky. Probably the least good pairing of the whiskies I tried.
Glenlivet Nadurra 16: An interesting pairing, as the chocolate seems to coax out a huge banana flavor from the Speysider and a little coconut as well. Nice.
Ardbeg 10: The chocolate tempers the peat quite a bit, but overall a surprisingly good match between the chocolate and smoky peat.
Macallan Cask Strength: The sherry gives the chocolate a fruity touch, and the chocolate acts to restrain the sherry. However, the combination of the chocolate with the sherry monster results in a bit of a boozy flavor, like a cheap cherry Schnapps.
Lagavulin Distiller's Edition: A great pairing: the refined oak, peat and sherry of the whisky all come through and mix beautifully with the chocolate.
Of the whiskies I paired, the Lagavulin Distiller's Edition was the clear favorite. In general, whisky opens up the chocolate well, but the chocolate flavor becomes so intense that it in turn tempers the whisky and can clobber its subtlies. However, strong peat mixed better than I expected, and I think the Lagavulin did particularly well because of its strong peat and sherry flavors combined with its "refined" quality. Of all the whiskies, it was the only one that the chocolate might enhance.
Based upon this experiment, I would expect chocolate to go best with refined tasting Islay whiskies. Not young malty peat monsters but whiskies where peat plays with refined oak. In addition to Lagavulin, I would expect good matches with chocolate to be Bowmore 18, Laphroaig 18, and Ardbeg Uigeadail.