Most of the good cookbooks on Pakistani cuisine are written in Urdu, except Dalda Ka Dasterkhwan. Kaukab Khwaja is pretty good and recently, Zubaida Tariq (a.k.a Zubaida Aapa from TV) came out with "Zubaida Aapa Kay Kitchen Say"
I have in my posession a very old book from the 50's, which is now out of print. I don't share it with anyone. It has only 33 recipes. I plan to open up my own restaurant in about 10 years. I will exclusively use those recipes.
Kaukab Khawaja's cookbooks are excellent. The recipes are always easy to follow and the outcome is always yummy. I have the chinese and continental cookbook of Kaukab's.