Preheat your oven to 180ºC.
Sift together the flour, cocoa and baking powder. Add the sugar and mix well. Lightly whisk the eggs with the vanilla extract and add to the dry ingredients. Stir in the hazelnuts and orange zest and combine to form a dough.
Shape into 2 narrow or 1 wide log and place on a baking tray lined with non-stick baking paper.
Bake for 30-40 minutes.
Remove from the oven and allow to cool. Using a serrated knife, cut the log into 1/2-1cm slices. Place the slices on a baking tray and bake at 140°C for 20-25 minutes or until the slices are crisp.
Serve with an espresso, cappuccino or vin santo.
