In a bowl, combine the kefir, egg, sugar, and oil. Mix thoroughly using a whisk.

Add 4 tablespoons of flour and baking powder, then mix together.

For a two-tone dough, separate into 2 parts. Transfer 1/3 of the mixture to a small bowl for the cocoa version.

In the large bowl with the remaining dough, add 16-20 tablespoons of flour, kneading to form a soft, slightly sticky dough. It may stick slightly, but avoid adding extra flour; use flour for dusting.

Add 2 tablespoons of cocoa and around 10 tablespoons of flour to the smaller dough portion. Knead into a soft, sticky dough that can be handled on a floured surface.

Divide the white dough ball in half to obtain 3 pieces: 2 white, 1 brown.

Roll each dough ball into a round sheet on a well-floured surface. Layer them with white + brown + white.

Roll up these layered sheets.

Slice the roll in half along its entire length.

Cut each half of the roll into pieces about the size of a large walnut.

Shape each piece into balls, taking care to maintain the layer separation. 

Lightly flatten them and place on a baking tray; bake at 200°C for 10-15 minutes.

While baking, prepare the glaze by beating egg whites with powdered sugar.

The cookies should not brown on top; check underneath for a light pink color to ensure they're ready. Over-baking will make them hard.

Immediately after baking, place 10 cookies in a deep bowl, add icing, and carefully mix with a spoon to coat evenly.

Place cookies on a baking paper-lined plate to dry. Repeat while cookies are hot to ensure the icing sets.

The icing dries quickly, perfect for serving with tea or coffee. 

Enjoy!