The cakes are filled with sweet bean paste or lotus seed, and at the very heart of each is a boiled egg yolk to symbolize the moon.

月饼里夹着甜豆沙或者莲籽，在馅的正中再放一个煮好了的蛋黄，象征着月亮。

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These small but dense cakes filled with lotus paste and a whole egg-yolk centre symbolise the full moon, and it is the accepted practice to share a cake with friends, family and colleagues.

BBC: Hong Kong��s enchanting homage to the moon