Smear the mold with a thin layer of vegetable oil or butter (not listed). Line the bottom and side with parchment paper cut to fit the mold.
Break in the eggs into a bowl, and beat in a double boiler until it forms a thick ribbon when the whisk is lifted.
Add the sugar and continue beating. Once it's well beaten to a point where you can almost write letters on the surface, smooth out the batter by beating for an additional 1 to 2 minutes at low speed.
Put the ＊ ingredients into a heatproof container and microwave at 600 W for 30 to 40 seconds.
Preheat oven to 170℃. Combine the ingredients and sift into the batter in 2 to 3 portions, folding in with a spatula with each addition.
Add in ＊ and mix swiftly.
Pour in the batter all at once from up high (making sure to pour in the last bits near the rim of the mold). Drop the mold down onto your work surface a couple of times to remove any air pockets.
Once the oven has been preheated, bake for 30 minutes. Once baked, drop the mold from a height of about 30 cm to prevent shrinking.
Flip it over on top of a sheet of parchment paper (Sorry, I'm using plastic wrap in this picture.)
Remove the mold and paper around the rim first, put the mold back on and let rest 2 to 3 minutes to flatten the surface.
Remove the mold around the rim and flip the cake over on your right palm. Gently place on a cooling rack and remove the mold and paper on the bottom.
Place the entire cake (with the cooling rack) in a plastic bag and let rest until completely cool.
When it's cooled completely, slice it to your preference.
Here's a petite chocolate cake I made with this same cocoa sponge cake (Recipe ID: 2077007).
I tried baking a cocoa-flavored sponge cake for Valentine's Day.
Beat the eggs thoroughly in a double boiler. You won't be able to slice the sponge cake nicely until it's completely cooled. If the skewer doesn't come out clean, bake a little longer at 170℃ until it is done.