Sift first four ingredients into mixing bowl. Slightly beat egg yolks and milk. Pour egg-milk mixture and melted butter into the dry ingredients; stir only until all ingredients are mixed.
Beat egg whites until stiff but still glossy; fold into batter with hazelnuts. Pour batter on preheated waffle iron. Bake 4 to 5 minutes, or until crisp and borwned.
Serve with maple syrup or Hazelnut butter.
Hazelnut butter (best if made night before). Combine 1 cup butter, 1/4 cup granulated sugar, 1/4 cup firmly packed brown sugar, 1/2 cup chopped, toasted hazelnuts, and 1 teaspoon vanilla. Cook until smooth and creamy.
You can freeze any leftover butter.