There is a large variety of mooncake (bánh trung thu) in Vietnam. It is one of the more popular pastries, specially during the Mid-Autumn Festival in September and October. This version consists of a flaky pastry crust and a sweet filling consisting of mung bean paste and durian. Durian has a reputation for being the stinkiest fruit in all of Southeast Asia, perhaps even the world. If you're traveling through the area, it won't take long before you start to recognize the smell. In this mooncake, the durian isn't super strong but it can't be ignored. If the taste or smell bothers you, you might want to try a different kind of mooncake. Sometimes salted egg yolk or pork fat is used to salt up the snack.
In Saigon, it is sometimes called bánh bía. They are usually round with red writing on them. Sizes vary from mini coined-sized, to larger coaster-sized.