Recipe by Terresa Murphy of
La Cucina di Teresa
Toast the hazelnuts in a 325ºF (160ºC) for 10 to 15 minutes, until they’re a deep golden brown color and the skins are peeling away. Remove from the oven and as soon as they’re cool enough to handle, rub the hazelnuts in a tea towel (or if they’re not too hot, with your hands), until as much of the loose skins come off as possible. Let them cool completely before grinding them up.
Terresa also says you can use almonds, which can be skinned by plunging them into boiling water for a minute, then draining them. And as soon as they’re cool enough to handle, pinching them to slide off the skins, then toasting them.
UPDATE: A couple of people noted in the comments that they had a bit of trouble coaxing the dough into a cohesive mass. It was recommended that if that happens, adding a small amount of water or a touch of butter (perhaps melted), is enough to bring it into shape. I haven’t tried them – or found them necessary – but if you do, I would add the smallest amount possible to bring the dough together. I posted some links to sites that have made them successfully after the recipe.
Storage: The cookies will keep in an airtight container at room temperature for up to one week.