This place specializes only on one very classical and Traditional dessert called "Kunefe".
I can confidently say that this is the best place to try this beautiful speciality if you are interested in traditional Turkish cuisine.
It is in Beyoglu. Address: 9/A Suslu Saksi Sk. Tel: 0212 251 82 74. From Taksim, you can walk down on Istiklal Street, it is on one of the small streets on the left had side.