Add egg yolk and sugar into a bowl. Whip with a hand mixer until thickened.
Add water and vegetable oil while mixing.
Add sifted cake flour and baking powder, and mix well with the hand mixer.
Mix the ☆ ingredients, and make a stiff meringue.
Add 1/3 of the meringue into the Step 3, and mix. Add the remaining meringue and fold it in.
Mix the ※ ingredients. Take out 1/3 of the Step 5 batter into a different bowl and mix with the ※ mixture.
Alternately pour in the plain batter and cocoa batter, and swirl around the circle twice with chopsticks.
Bake in the oven preheated to 170℃ for 40 minutes.
Put it up side down to cool (for 1.5 ~ 2 hours)
Story Behind this Recipe
I got used to making a plain chiffon, so I challenged myself to a new recipe I thought if I made a normal cocoa chiffon, I might fail because of the oil from tge cocoa powder, so I tried with a cocoa marble chiffon first.
The amount of the ingredients for each mold size: 20 cm diameter mold : 5 eggs, 18 cm diameter mold : 4 eggs, 17 cm diameter mold : 3 eggs, 15 cm diameter mold : 2 eggs.