Put hazelnuts on a baking sheet and bake for 12 minutes, or until they begin to brown. If hazelnuts are still in their skins, bake until skins begin to darken, or for blanched nuts, until they turn golden. Remove from oven and let cool. If hazelnuts are still in their skins, place nuts in the center of a clean dish towel, fold the towel around the nuts, and rub vigorously between both hands for 15 seconds to release the skins. Discard skins and reserve the nuts.