1. In a large bowl, combine flour, hazelnuts, sugar and salt.
2. Make a well in center and mix in butter and vanilla extract to form dough.
3. Place dough in refrigerator until chilled.
4. Preheat oven to 375F.
4. Form dough by hand into balls about 1 inch around.
5. Place on ungreased cookie sheets and bake for 15 minutes.
6. Cool slightly on wire rack. While still warm roll hazelnut balls in confectioners sugar. When cool, roll again in confectioners sugar.