White sugar cake sponge (also called white cake sugar and white pastry sugar) is a type of Chinese pastry. It is one of the most common pastries in Hong Kong. Overseas, however, it is much more rare in Chinatown bakery shops.
While it is called a "cake", it is not served as a circular round cake. It is usually purchased as an individual square piece or a mini triangle. The cake is white in color. The consistency is spongy and soft. The taste is sweet, and sometimes has a slightly sour taste due to fermentation of the batter prior to cooking. Like most Chinese cakes, it is steamed, giving it a moist, soft, and fluffy texture, as opposed to a dry and firm one. If left exposed to the air, it hardens quickly. It is usually kept under some cover to preserve moistness. It is typically served hot, because when it is cold it is not as soft and moist. The batter is either poured over a bowl in a steamer, a Chinese steamer cloth or aluminum foil. If made from brown rice flour and brown sugar it is called a brown sugar sponge cake.
A Vietnamese version of the cake, called bánh bò, differs from the Chinese version in that it often uses coconut milk as an ingredient, and does not have the sourness that often typifies the Chinese version.