Pour the sugar and the egg-whites into a metal or glass fireproof bowl.

Stir well with a whisk until a homogeneous mixture is obtained.

Prepare a small saucepan with water and set over moderate heat. The water should be heated without boiling. Set the temperature to low heat and place the bowl with the egg-whites on top of it. Continue stirring the mixture over low heat at a water bath.

Stir the egg-whites mixture in a water bath until the sugar is finally melted.

Add the walnuts.

Stir the mixture for another 4-5 minutes.

Remove the bowl from the heat and allow to cool for 5-10 minutes. Then add the flour.

Stir until smooth. You need to get a thick and sticky mixture.

For the baking, choose a large, flat baking pan and cover with parchment paper.
With a teaspoon, pour some of the mixture onto the parchment paper. The amount is about 1 tsp. Place the walnut cookies at a distance because they spill a lot during baking.
Bake for about 10 minutes at a moderate temperature (about 170 degrees) until they get a nice tan.