Preheat over to 200°C.
Combine flour, hazelnut powder, sugar and powdered chocolate.
Melt the butter in the microwave or in a bain marie.
Add to the mixture with an egg.
Mix you get an homogeneous paste.
Cut the dark chocolate into small pieces and incorporate into the dough.
Make small balls and place them well spaced on a sheet of parchment paper placed on a plate.
Bake for 12 to 15 minutes.