Someone gave us a bottle of chocolate extract a few years ago. We decided we didn't like it very much, so we can send you a bottle that's about 7/8ths full, if you like.

Chocolate extract is very like vanilla extract in its make-up - that is, the essence of the bean distilled in a solution of water and alcohol. One manufacturer says chocolate extract contains the "volatile top notes" present in raw cocoa beans. These smells and flavors are lost when the beans are processed with heat and pressure, resulting in a significant loss of flavor. Using chocolate extract is a way to replace the flavor that has been lost. Apparently we don't care for the flavor that has been lost, but that's just us.

If we haven't piqued your curiosity enough now to get your own bottle of chocolate extract, you can certainly use vanilla extract instead. You could leave the chocolate extract out entirely, or, if you're concerned that your recipe have exactly the right amount of liquid, you could use the same amount of water instead (for an ice cream recipe, it's not going to matter at all. If it were a fussy pastry, you might need to be concerned about replacing the amount of liquid). Or if you're determined to add a little alcohol to your recipe, you could probably use cognac or some other rather neutral spirit.