Hazelnuts, also called filberts, are sold with the brown outer skin removed or with it still on the nut. Since the skin has a bitter flavor, look for nuts that already have the skin removed. If you purchase hazelnuts that still have a skin, bake them at 350°F. 10-15 minutes or until the skins begin to flake. Place the warm nuts, a handful at a time, in a clean dish towel and rub to remove most of the skin.