Is a ... spread? sauce? I think it's European in origin and very popular there, though it's easily available here too.
It's a thick, sticky, chocolate-hazelnut kind of goo that is spread on pancakes (IHOP has crepes with it) or I guess, on ice cream or cake. I've tried it and it's so sickly sweet I never want to taste it again, but as I said, it's very popular in Europe, and presumably France.
I think, therefore I judge.