Gently melt 1/3 cup of butter. Mix it with the flour and salt adding water to make a mixture having a buttery texture. Knead the dough onto a pastry board until smooth.

Give the dough a round shape and leave to rest in a cold place for ten minutes or so. Then roll it out making a layer about 0.2 inches thick.

Put the remaining butter in the centre, flattening it slightly, folding the four edges of the dough layer to enclose the butter. Leave to cool for ten minutes. Roll out the dough using a rolling pin onto a lightly floured pastry board, making a rather thin layer.

Fold in the four sides, and flatten the dough. Repeat this operation four times. Roll out the dough very thin, cut out disks using a large glass brim, fold the disks in half, pressing the edges with your fingers to make crescents.

Brush the surface with the two beaten egg yolks, sprinkle generously with coarse-grained sugar (preferably with a crystalline texture).

Bake in a hot oven until puffy.