Chop the butter into pieces and place in a warm place to soften. separate the yolks from the whites /keep 4 protein /. with a mixer beat the butter with half dose of sugar until fluffy cream. continuing to whisk, add the 6 egg yolks. add the yogurt and lemon zest, mix well.

Separately, beat egg whites with salt until peak, add sugar and beat еще2 minutes. to shift the beaten egg whites into the cream and carefully mix everything with a spoon.

Add the sifted flour with starch and baking powder. mix everything carefully with a spoon.

Put the dough in, prior greased with butter and sprinkled with flour a baking dish /30 cm in length and 10 cm in width /. bake in the oven at 180" for about 30 / 40 minutes. allow to cool.

Optionally, sprinkle top with powdered sugar.