Preheat oven to 350ºF. In a medium bowl, whisk together flour and salt; set aside.

In a separate bowl, beat butter and sugar until creamy. Mix in vanilla. Add flour mixture and stir until just combined. Stir in nuts.

Roll into 1-inch balls and place 1 inch apart on ungreased cookie sheet. Bake for about 10 minutes or until firm to the touch, but not cracked or browned. Remove from pan and roll in powdered sugar. Let cool completely on wire rack, then roll in powdered sugar again, or right before serving.