# Rest the margarine at room temperature for 2 hours at least, before starting to prepare the cookies.
# Place the softened margarine into a deep bowl, add egg, castor
sugar and
yogurt into the bowl. Mix it by a fork or a beater.
# Add vanilla, sodium bicarbonate. Add sifted
flour into the mixture little by little while kneading the dough, until it reaches to medium consistency.
# Divide the dough into 2 equal pieces. Add
cocoa one of the dough pieces, and knead it until the piece turns into brown totally. Keep the second one pure.
# Roll out the brown dough piece larger than a flat service plate. Roll out the white one also and place it onto the brown one. Roll it for a while without forcing on it too much to make them stay together.
# Roll the dough firmly and cut this roll into pieces, each has thumbnail thickness.
# Place the cookies onto the greased baking tray with some spaces between each of them. Place the tray into the oven, which is preheated to 374 F.
# Bake it for a short time. Do not let the cookies turn to yellow.
