Moon cakes are typically round, symbolizing the full round moon of the mid-autumn festival. They are usually made with four egg yolks, representing the four phases of the moon, and are sweet, filled with sweet bean or lotus seed paste.

There are savory types as well and these days, you can even get them from Haagen Dazs. Read more about moon cakes and how to make them from Rhonda Parkinson, Guide to Chinese Cuisine.

History of the Moon Cake

According to chinese moon cake festival one legend, it was with the help of the mooncake that the Ming Dynasty established. Rebels used the festival as a method to convey their plans for revolt. They ordered the baking of special cakes to commemorate the festival.

But what the Mongol leaders didn’t know was that secret messages were tucked into the cakes and distributed to allied rebels. On the night of the festival, the rebels successfully attacked, overthrowing the Mongol government and establishing a new era, the Ming Dynasty.

Source: http://gochina.about.com/od/eventsfestivals/p/MoonFestival.htm