This is one of those places that is so good, and so small and perfect, that I hesitate to spread the word. However they are already on dianping so the secret is out. It's just off Cao Jia Alley, where I had great spring rolls last week.
Dan hong gao is more of a winter than a summer snack, but I still had to wait several minutes to make an order in the middle of the afternoon on one of the hottest days so far. They were also selling bing fen (cool clear jelly with sugar syrup on top) and a lot of customers were ordering that on the side.
They have a menu of several kinds of dan hong gao, many of which you would not find anywhere else. By far the most popular is 'guai wei', strange flavour. I also ordered a 'san xian'. I don't usually go for meat-filled dan hong gao, but these were so, so good. The outsides were unusually crisp and the fillings were amazing. I also asked the vendor to make my usual peanut butter and strawberry jam but I didn't like the peanut butter.
Sweet, spicy, and savoury insides for the guai wei:
Stepping into Cao Jia Alley is like stepping into the past. While I was there a delivery man with big milk cans on his bike came by, and people came out with their containers to get milk from him.