I want to know is there any service in Islamabad/ Rawalpindi through which one can send cakes via home delivery and at night !

14thstreetpizza. But they only have 2 varieties

TCS does that, but in morning only.. also one day delivery time.. also mithai from niralla... but i guess thats not what you are looking for..

Just eat Islamabad solved my problem :)

may be it hob nob?

Yeah: there is very well known name Shop Arcade that provides cake delivery in Pakistan. They provide you the free and fastest cake delivery in PAKISTAN. I'll try this shop many times and i always received my order on time even at mid night. Enjoy