What festival is the moon cake?

Do you mean what festival it is to eat moon cakes? It's Mid-Autumn Festival.

Mid-Autumn Festival, also known as the Full Moon Festival, Mid-Autumn Festival, Mid-Autumn Festival and Reunion Festival, is a traditional folk festival in China. The Mid-Autumn Festival originated from the worship of celestial phenomena and evolved from the worship of the autumn moon in ancient times. At first, the festival of "offering sacrifices to the moon" was held on the day of "Autumn Equinox" in the 24 solar terms of the Millennium, and later it was moved to August 15th of the lunar calendar. In some places, the Mid-Autumn Festival is set on August 16th of the lunar calendar. Since ancient times, Mid-Autumn Festival has had folk customs such as offering sacrifices to the moon, enjoying the moon, eating moon cakes, playing with lanterns, enjoying osmanthus and drinking osmanthus wine. It has been circulating for a long time.

Eating moon cakes is actually a part of the custom of "offering sacrifices to the moon", which is a very old custom in China. Moon cakes are offerings to worship the moon god in ancient Mid-Autumn Festival, and they are also seasonal food for Mid-Autumn Festival. In ancient times, the moon was sacrificed every Mid-Autumn Festival night. Set up a big incense table and place sacrifices such as moon cakes and fruits. Under the moon, put the moon statue in the direction of the moon, and the red candle burns high. The whole family takes turns in Yue Bai, and then the housewife cuts the reunion moon cakes. As an offering to worship the moon god, moon cakes have a long history.