
Besides the taste is as soft as cotton....yum yum (that's why it called cotton cake), I was so curious because to make this cake is a bit tricky. Especially when you beat the egg white and mix it with the flour mixture.
Another tricky part is in the baking process, the temperature can not be overheat. Bake at 160˚C until it's rising high, then reduce to 150˚C and continue baking until cooked, about 35 minutes. And then after baking (this is a tips from Rachmah), don't leave the cake too long in the cake tin, invert immediately onto cooling rack so that the cake won't shrink.

Mocha Cotton Cake
Copied from Arfi of Homemades
Source: Rachmah Setyawati, modified from Tulip Baking Demo.
Ingredients :
60g butter
50g plain flour
15g cocoa powder (Dita-I used 5 g cocoa powder and 10 g instant coffee powder)
73ml milk
5 egg yolks, whisked loosely (Dita-I used 4 egg yolks)
5 egg whites (Dita-I used 4 egg whites)
120g caster sugar
3g cream of tartar (optional)
1/2 tsp mocca paste (Dita-I didn't use mocca paste)
Directions :
Preheat the oven to 160˚C.
Heat the milk in a small saucepan until just hot, but not bubbling. Pour into the loosely whisked egg yolks, mix well. Set aside.
Heat the butter until bubbling. With the stove off but the saucepan still on the hot stove, add in the sifted plain flour and cocoa powder together into the hot butter. Whisk until smooth. Add in the mixture of egg yolks and milk. Whisk until smooth. Set aside.
Whisk the egg whites until foamy, add in cream of tartar. Add in caster sugar bit by bit until the sugar has all used and the egg whites gone soft peak. Spoon out a bit of the meringue mixture and add into the chocolate mix, combine well. Pour this mixture into the rest of the meringue, fold in gently, just careful not to knock out the bubbles.
Pour into a lined (not greased) 20x20x4cm square cake tin and bake at 160˚C until it's rising high, then reduce to 150˚C and continue baking until cooked, about 35 minutes.
And then I poured the cooled cake with cheese frosting made from cheese spread, corn flour, milk and sugar (mix and boil milk, sugar and cornflour, remove from heat, add cheese spread).
