First, take out just one piece of dough from the refrigerator, roll it out very thinly on a floured work surface and cut it into 10 x 10 cm rectangles. Put the resulting dough scraps back in the fridge for now.
Put about 1 heaping tsp of walnut filling on each dough rectangle, spread it evenly on top, leaving about 0.5 - 1 cm wide border from each side, and press the filling to the dough slightly.
Roll up each dough rectangle with the filling as tightly as possible.
Spread the filled rolls, seam side down, on a baking tray lined with baking paper.
Repeat with the other two pieces of dough and with the leftover dough from the refrigerator.
Once the first baking tray is full, spread the remaining cookies on a second baking tray.
Bake the cookies first on the first baking tray, then on the second baking tray in a preheated oven at 356 °F (180 °C) for about 25 minutes each until lightly golden brown.
Let the cookies "Barmak" cool down and dust them with powdered sugar.