Try this: Atelieramaro.pl
Certainly the cream of the crop for the culinary connoisseurs but maybe lacks the ambiance for a Christmas dinner, it's not cheap either by any standards. 1000zl for 2 with their 5 moments menu, a glass of champagne and the vodka taster menu instead of wine. I dared not even look at the wine list.
I would suggest Ale Gloria next to the Sheraton.