You must try Daulat Ki Chaat, it's a winter delicacy!
Try Kulle Ki Chaat - Gali Lohe Wali and Shyam Sweets (near chawri bazar metro station)
Ashok Chaat Bhandar, Kuremal Kulfi, In Kinari you will find JB Kachori Wala
Veg kathi kebab at chhotey lal in sita ram bazaar
Shyam Sweets is excellent, especially their Bedmi Poori & Kachori. Also Gianis Di Hatti for their Chole Bhature.
Go and try chat from 'hira lal chaat corner'
Ashok Chaat Bhandar is AMAZING!
Kuremal kulfi is a must try for desserts
You can Try anything is worth eating there