Ma lai gao (马来糕, Malay cake — a dim sum preparation with no direct Malay origin, though the name persists) is a steamed sponge cake of unusual texture — soft, slightly bouncy, with a deep caramel-brown colour from the brown sugar or molasses used in the batter, and a pleasantly sweet flavour with malty undertones. The traditional version uses a fermentation technique in which the batter rests overnight — the yeast present in the wheat flour and the alkaline baking powder interact to produce a slightly tangy, complex flavour and an extra-light texture. A correctly made ma lai gao should have an open, uniform crumb and a surface that is completely smooth and slightly shiny.
The fermented version: 200g plain flour + 5g baking powder + 150g brown sugar + 150ml warm water. Mix together and rest uncovered for 8-12 hours at room temperature. The batter will become slightly bubbly. Beat 3 eggs and add to the fermented batter. Add 3 tbsp melted lard (or neutral oil), 1 tbsp evaporated milk, and 1/2 tsp vanilla extract. Mix. The batter should be smooth and pourable. The quick version: Add 3g additional baking soda for an unfermanented, same-day batter — the result is slightly less complex but still correct. Steaming: Pour the batter into an oiled round or square cake pan. Steam over boiling water for 25-30 minutes — the cake is done when a skewer comes out clean and the surface springs back when gently pressed.
Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009)