Selling like hot cakes: The demand for moon cakes spikes at Mid-Autumn Festival. Photos provided to Shanghai Star

The quintessential Shanghai snack can be found all over the city, but Wang Ying tracks down the most authentic pastries at Zhen Laodafang.

With the Mid-Autumn Festival fast approaching, the demand for moon cakes is rising, as evidenced by the long lines on East Nanjing Road outside the renowned pastry shop Zhen Laodafang.

People who are new to Shanghai may struggle to tell the difference between the various "Laodafang" brands in the city, including Xiqu (western region) Laodafang, Nanqu (Southern region) Laodafang, Dongqu (Eastern region) Laodafang and Zhen (Real) Laodafang.

But true locals know that only at Zhen Laodafang can you get the genuine taste of xianrou yuebing, which literally translates as fresh pork moon cake, a must-try for the traditional festival.

Zhen Laodafang evolved from a tea snack store, which was established by pastry chef Chen Kuifu on Dongjiadu Road in 1851. Between 1920 and 1921, Chen expanded the business by opening new branches on Nanjing Road and the Jing'an Temple area. By inviting pastry chefs from Anhui province, Laodafang offered a wider variety of products including crispy candy, pastries, pork dumplings, smoked fish, edible oil and noodles.

The pork dumplings are the origin of the xianrou yuebing, says Yao Songming, deputy general manager with the Zhen Laodafang Food Company.

Unlike regular dumplings that have wrappers made of a thin layer of flour, Laodafang's pork dumplings weigh 42 grams each, and are made of crispy pastry in a shape of a crescent moon.