Actually the two things they do *not* consider "food" are candy and chewing gum. But chocolate does not qualify as candy by which they mean hard candy like Werthers or such.

So regardless of whether it's in your carry-on or checked bag (which in any case you'll collect before going through customs at most airports) you *must* declare it. But it shouldn't be a problem. Fwiw it might cause you to get sent to a secondary inspection where they'll take one look at it and say ok. But that could end up adding some time if you're on a tight connection. Especially if you're landing in California where they have agricultural inspections.

The US and Canada operate under a different system from Europe. In Europe you only need to declare things if they're over the limit. In the US and Canada you must declare any food, alcohol, or tobacco even if you're under the limits.