I am not sure Hidden Treasure applies in that it has been listed in certain guide books on occasion, but it is on the small side and seemed, on our visit, to be quite a 'hidden' gem.
I give you Zum Weissen Rauchfangkehrer.
This central Vienna restaurant was our stop after an evening at the opera and surpassed all expectations of which we had set fairly high based off of reviews and books.
The cuisine was fantastic and the service and wine selection unsurpassed and rarely matched even. The piano was beautiful ambience to the gorgeous decor. We hit the spot a bit later than most perhaps which rather that create a rushed feeling by our server made it feel almost private in the exemplary attention we received.
I know we will never pass up the opportunity to eat there on any future visits and we strongly recommend if you are there please enjoy a truly amazing experience.