I found this cake design and recipe by Rice & Four so attarctive that I baked one straighaway!
10gr cocoa powder
30ml hot water
5 egg yolks
75gr all-purpose flour
5 egg whites
pinch of salt
¼ tsp cream of tartar (optional)
75gr caster sugar
You will need a 10cm deep cake-tin 20cm in diameter, or a 18 x 18cm square tin.
Preheat the oven at 150˚C. Line the baking tin with parchment paper, but do not grease the sides.
Mix the cocoa powder with the hot water and set aside.
In a bowl, put beat the 5 egg yolks plus the 1 egg. Beat until the mixture becomes very thick, smooth and pale. Slowly add oil, mixing well on the lowest speed, or just whisk it by hand. Then slowly add the milk and mix again.
Divide the flour into 2 parts, sift each part into the bowl, mix well before adding more, but do not over-mix.
Beat egg whites with the salt, cream of tartar (optional) and sugar until they forms almost stiff peaks: the tips should remain a little droopy – if the meringue is not stiff enough, the cake will not rise well; if the meringue is too stiff, the cake surface may crack during baking and/or deflate after it comes out of the oven.
Go back to the flour-yolk mixture, whisk to blend with a balloon whisk for about 10 seconds until the mixture is well-incorporated. Add 1/3 of the meringue, to ‘loosen’ the yolk mixture, then gradually fold gently the remaining meringue.
Divide the batter in two equal parts. Add 3 tablespoons of batter into the cocoa mixture, stir well then pour it back to the original batter and fold gently with a spatula.
Put 3 tablespoons the cocoa mixture into the middle of your tin; then, add 3 tablespoon of the plain batter into the middle of the cocoa pool and repeat till all the mixture is used, alternating between cocoa and plain mixture spoonfuls, gently shaking the tin occasionally for the mixture to spread evenly.
Place a large baking tin at the bottom rack of the oven, fill it with boiling water (1cm approx). Place the cake in the middle or low rack abd bake for 50 – 55 minutes.
The cake is done when it’s springy to the touch and has a nice golden brown colour. Let it cool in the tin for 10 minutes, then turn it upside down onto a cooling rack. Handle gently as the cake is very soft. Remove the parchment paper and let the cake cool completely.
Store in the fridge and use in 2 days.