Gulam Bakery is in Mandiri, Patna, towards Budha Colony. You turn inwards at the bridge and temple at Mandiri and take first turn right. It is in a nondescript place without any signboard but many people know it because it is popular among cake lovers. In particular seasons there is a crowd of people waiting for cakes to be baked. You take your cake ingredients and they will mix them and bake the cake in your presence. Or you come, buy the ingredients and have the cake baked. They are customer friendly. The only weak point is: they mix the ingredients manually that could be considered unhygienic.