Mooncake is a Chinese bakery product traditionally eaten during the Mid-Autumn Festival (Zhongqiu). The festival is for lunar worship and moon watching, when mooncakes are regarded as an indispensable delicacy. Mooncakes are offered between friends or on family gatherings while celebrating the festival. The Mid-Autumn Festival is one of the four most important Chinese festivals.
Typical mooncakes are round or rectangular pastries, measuring about 10 cm in diameter and 4–5 cm thick. This is the Cantonese mooncake, eaten in southern China (Guangdong, Hong Kong). A rich thick filling usually made from red bean or lotus seed paste is surrounded by a thin (2–3 mm) crust and may contain yolks from salted duck eggs. Mooncakes are usually eaten in small wedges accompanied by Chinese tea. Today, it is customary for businessmen and families to present them to their clients or relatives as presents, helping to fuel a demand for high-end mooncake styles. The caloric content of a mooncake is approximately 1,000 calories (for a cake measuring 10 cm (3.9 in)), but energy content varies with filling and size.
Mooncakes in Japan are known as geppei, a direct translation of the Chinese name. They are associated with Chinese culture and are sold all year round, mainly in Japan's Chinatowns. Azuki (red bean) paste is the most popular filling for these mooncakes, but other sorts of beans as well as chestnut are also used. Unlike some types of Chinese mooncakes, mooncakes in Japan almost never contain an egg yolk in the center.