As only Utrecht has wharves at the canal-level from which quite a lot have been converted to restaurants/bars, and Amsterdam doesn't - I agree it probably is Utrecht. Your best bet is to check out google maps (street name: Oudegracht) and check the names of the places or street view if anything might ring a bell! Many of them have "cave-like" interiors.. Maybe Het Oude Pothuys could perhaps match your description as it's the first I'm thinking off, but there are quite a few other places like this!