• I use a 8 x 3 inch round cake pan. Line the round cake pan with parchment paper all around. It's okay to have some extra on the sides as you can fold it down
• Fill up the steamer with water, enough to steam for at least the first 30 minutes. Bring it to a boil and then lower to medium to keep it on a stand-by

For the cake batter:

• Combine cake flour, salt, baking powder, and cocoa powder in a bowl. Set aside
• Crack eggs into a mixing bowl. Beat over high speed (speed 8 on Kitchen Aid) for about 1 minute. Then gradually add in sugar in 3-4 batches. Continue to beat until the mixture is pale and creamy, about 10 minutes with a stand mixer on high speed (speed 8 on Kitchen Aid), about 15-20 minutes with a hand mixer. The volume would have tripled by now. The mixture will be thick and you can write figure 8 and it won't disappear immediately. We call this "ribbon stage". It is important to reach a ribbon stage or your cake will be dense
• Stop the mixer. Crank the heat on the stove back up so the steamer is ready. Add in cake flour mixture in 3 batches, alternating with the oil in batches. Use a whisk to gently swipe and fold over flour and oil. Just mix until you no longer see pockets of the flour mixture. Switch to spatula to make sure everything is properly combined. Don't overmix either or your cake will be dense and tough
• If you want to make a 2-layer cake, pour 1/2 of the cake batter into a prepared pan. Drop the pan on a counter a few times to pop and large bubbles. If you plan to make 3-layer cake, pour 1/3 of the cake batter. I suggest not making more than 3 layer as the cake batter has to sit out for too long. Drop the pan on a counter a few times to pop any large bubbles

Steaming:

• Put the pan inside the steamer. Wrap the lid with a towel to prevent condensation from dripping on the surface of the cake. Steam over high heat for 10 minutes.
• While the cake is steaming, divide the mung bean paste into 2 portions, 150 g each for a 3-layer cake. For a 2-layer cake, you don't need to divide. Roll each one in between two parchment papers into a round circle, about the same size as the pan. They don't have to be perfectly round, just do your best. You will have 1 circle if you do 2-layer cake and 2 circles if you do a 3-layer cake.
• Back to the cake: Uncover the lid and check on the cake. The surface should be dry to touch and bounce back when you gently press on it. Remove from the steamer
• Drape one of the mung bean paste round on top of the steamed cake. Use a rubber spatula to make it neat and spread out as evenly as possible.
• Carefully pour in the next 1/3 of the batter on top of the mung bean layer. Give the pan a few taps on the counter to pop any large bubbles. Put the pan back into the steamer and steam again on high heat for 10 minutes
• Check on the water level when you remove the cake from the steamer. Fill it up with hot water if needed and bring it back to a boil over high heat.
• Repeat this sequence again by draping the next mung bean paste round on top of the steamed cake, then pour the last 1/3 of the batter on top. Give the pan a few taps to pop the bubbles and then steam over high heat for 20 minutes. The surface of the cake should be dry to touch and bounce back when you press on it

Cooling:

• When the cake is done, remove it from the steamer and leave the cake out of the pan by lifting the parchment paper and letting it cool down on a cooling rack. This way the bottom of the cake won't be wet and soggy
• Let the cake cool down completely before slicing