Havmore and gulati's at malcha marg its just so good
Even moti mahal delux has a good butter chicken
Rajendra da dhaba in Safdarjung enclave.
Dhabhaa is the best option, full desi and yum.
Purani Delhi- 6 in Gujranwala town , There is a best butter chicken in all around delhi.
Minimum it will cost you around 600-700INR, There's a restaurant called Taj Chicken, it is good for it.