Wash and peel 200g of fresh water chestnuts. Place them in a sealed plastic bag and gently crush them with the flat side of a knife or another heavy object. After crushing, remove them from the bag and chop them into small, even pieces. This method prevents the water chestnuts from splattering during preparation and ensures a more consistent texture.

In a large bowl, combine 150g of water chestnut flour with 350g of water. Stir the mixture thoroughly to form a smooth batter. For a silkier texture, strain the batter through a sieve to remove any lumps. This step is crucial to ensure a smooth final texture for the cake.

In a saucepan over medium-low heat, melt 75g of white granulated sugar until it turns a golden caramel color. Be patient and stir occasionally to prevent burning. Once the sugar has caramelized, add 350g of water, 75g of rock sugar, and the prepared water chestnut pieces. Cook the mixture until the sugar has completely dissolved, then remove it from heat.

Stir the batter again to ensure the flour hasn’t settled at the bottom. Take about 50ml of the prepared batter and pour it into the caramel syrup, stirring quickly to combine. Then, pour the entire caramel syrup mixture back into the remaining batter. Mix thoroughly to create what is known as the "raw-cooked batter." This step is key to achieving the signature chewiness of the cake and prevents it from separating into layers during steaming.

Pour the mixture into a prepared tray, smoothing out the surface. Once your steamer water is boiling, steam the cake over medium heat for about 20 minutes, or until fully set. Allow the cake to cool completely before attempting to remove it from the tray. The cake should have a beautiful golden hue and a satisfyingly bouncy texture.