Beat 5 eggs (no need to separate them) with sugar until it’s three times in volume. Using a spatula, fold in flour by thirds; be very gentle with the dough so you don't over mix it and lose the fluffiness.
Bake it for 30 minutes, check it with a wooden toothpick. If the cake is ready, dough should not stick to the toothpick.
Add 3 tablespoons of cacao into flour, mix together well. Add same way by thirds into dough.