Preheat oven 350 degrees. Spread the walnuts on a baking sheet and toast in the oven, tossing occasionally until fragrant, 6-8 minutes, let cool. In a food processor , process the walnuts until finely ground. In a large bowl, whisk together walnuts, flour, cinnamon and salt, set aside. using an electric mixer, beat the butter, 1/3 cup sugar on medium high until light and fluffy, 2-3 minutes. Beat in the vanilla. Reduce mixer speed to low and gradually add the flour mixture, mixing until just combined. Do not over mix.
Shape the dough into 1-inch balls and place 2 inches apart on baking sheet. Bake 12-14 minutes, until just beginning to brown. Let cool slightly on baking sheet, then transfer to wire rack. Place the remaining 1/3 cup powdered sugar on a platter. Roll cookies in sugar to coat, then dust with cinnamon. Makes about 36 cookies.