How to make
Beat the yolks with the sugar, add the vanilla, yoghurt, orange zest, oil, freshly-squeezed orange juice with the baking powder and flour.
Finally add the beaten to snow egg whites.
Set aside a small part in a bowl and add the cocoa to it.
Pour the dough into a tray and the cocoa mixture in the middle.
Bake in a preheated oven to a dry toothpick.
