# Put soft butter, sunflower oil, yogurt
and castor sugar
into a deep bowl. Blend or mix it by a whisker well.
# Then, add cacao, starch, vanilla, salt and baking powder. Mix it for a few times by a spoon.
# Finally add flour
into the mixture during the kneading, until the dough reaches medium consistency.
# Cover the dough and rest for about 15 minutes.
# At the end of the resting time, pick pieces from the dough which are a bit smaller than walnut
s. Roll them between the palms, then place the over a grater, force over the cookies a little. Place the shaped cookies the greased baking tray. Place the tray into the oven which is preheated to 375 F for 10 minutes. Bake the cookies for about 15 minutes. Cool the cookies at room temperature, then you may serve.