*Pandan milk: Blend 12 g of pandan leaves with 180 g of milk, extract 170 g of pandan milk.
Combine plain flour, rice flour, baking powder, baking soda and cream of tartar, sift through and mix well. (Reminder: Baking soda helps egg sponge cakes to bloom, do not omit. Cream of tartar is acid to neutralize the baking soda so that there won’t be weird taste.)
Bring the water of steamer to the boil for later use.
Add salt and sugar to eggs, beat until combined.
Combine 1 Liter of plain water with 400 ml of hot water (from electric thermo pot) in a large steel bowl to yield warm water with temperature about 45°C/113°F.
Dip mixing bowl in warm water, beat egg mixture over medium-high speed for 5 minutes until very stiff. (Reminder: Beating egg mixture over warm water will shorten the time for it to become stiff.)
Add in flour and pandan milk alternatively in a few batches, fold until well mixed with spatula. Add in corn oil, fold until well mixed.
Fill batter into 6 lined baking cups (7.5-cm) until 90% full, then arrange in steamer rack.
Put over steamer, steam over medium-high heat for 14 minutes.
Unmold the smiley egg sponge cakes and cool on a wire rack.
This recipe yields 6 (7.5-cm) sponge cakes. The nutritional value for reference is for 1 sponge cake.