In a large bowl whisk together the flour, sugar, salt and hazelnuts. Then, add vanilla and butter. Once the ingredients start to come together, move to a lightly floured surface and knead to form a dough. Wrap in parchment or plastic wrap and refrigerate 2 hours.
Roll dough into small balls, then place them on cookie sheets. Chill them while oven is pre-heating.
Pre-heat oven to 350.° Line 2 cookie sheets with parchment paper.
Bake for 10-12 minutes. Let sit about 1-2 minutes (while the cookies are still warm) then roll in sifted confectioner's sugar. Let cool and then roll again in the confectioner's sugar.