Lightly flour a work surface and lay a pastry sheet on it with the short side toward you.
1 sheet puff pastry dough
Spread hazelnut-cocoa mixture on the pastry sheet up to ¾ of its height. Sprinkle the hazelnuts along the width of the pastry.
1 cup hazelnut - cocoa spread, ¼ cup chopped hazelnuts
Roll the pastry sheet from bottom to top. Brush lightly with egg white. Slice the roll into 8 sections and arrange the sections flat on the parchment paper.