Layer cookies between sheets of waxed paper in an airtight container; cover. Store in the refrigerator for up to 3 days or freeze for up to 3 months. To serve, thaw cookies if frozen.
Place hazelnuts on a shallow baking pan. Bake in a 350° oven for 5 to 10 minutes, shaking the pan once or twice. Cool. To remove the papery skins from the hazelnuts, rub the nuts with a clean dish towel. Place nuts in a blender or food processor. Blend or process until nuts are ground, using a quick start-and-stop motion to help prevent over processing the nuts.