The low-proof whiskey channels the flavor of red-hot cinnamon candies and is oddly easy to toss back as a shot, which is how most people take it. Cinnamon whiskey may start sweetly in its pure form, but it quickly rises from kindling to an inferno of a finish, with a lingering burn that kicks like an angry mule. Perhaps this is why the spirit has proved so popular: It’s exhilarating in its rocket-fuel-like quality and has even sparked competition among a series of big-brand imitators.