Add in powdered sugar, egg white and cocoa powder. Run the processor until everything is well blended. You will have a soft and sticky dough. If your dough doesn’t hold well, just add a little more hazelnut.
Use a teaspoon and drop cookies on the parchment paper.
Bake for 8-10 minutes and let them sit in the baking sheet for 2 minutes after they are removed from oven. Then transfer on a wirerack and let them cool completely.