The Chocolate Room is one my favorite hang out spots after college since it is pretty cheap and reasonable.
The ambience of this place is very chilled out. They have simple tables and chairs and beige walls. They have shelves on the walls on which they have lined up their wares which is a pretty cool sight as well.
They serve variety of sundaes, pastries, mocktails and other desserts as well. They have long list to choose from in each category. Cost for two would come up to Rs 700 approx which is very good.