An Italian liqueur made largely from hazelnuts and flavored with other nuts and berries. It has a wonderful flavor and is good in mixed drinks (it's good to make a white russian with it.) It's also used in baking--I have a hazelnut biscotti recipe that requires it, as well as things like tortes and the like which are benefitted by a hazelnut flavor.

It's also hideously expensive, but a little goes a long way. You don't get wasted on Frangelico.