In a large bowl, crack 1 large egg and add 55g sugar and 1 tsp vanilla extract in .Whisk until light and fluffy
Sift dry ingredients including 100g flour, 1tsp baking powder and 4g custard powder to the bowl. Mix well
Add ¼ tsp salt, 80ml milk and 12g oil to the mixture. Whisk until the batter is smooth.
Prepare 4 cupcake mold and put 4 cupcake liner inside, divide the batter evenly to cupcake mold.
Boil water in a steamer and put the cupcake mold inside when the water starts to boil. Cover the steamer with a clean kitchen cloth and cover the lid, steam under medium heat for 17 minutes
Take the cupcakes out, wait for it to cool down and enjoy.