Heat oven to 350° F.
Add 1 cup of powdered sugar to small shallow bowl. Set aside.
In mixing bowl, whisk together flour, chopped walnuts and salt and 1/3 cup powdered sugar. Optional: add cardamom
Beat butter to pale (about 3 minutes).
Add vanilla extract. Slowly add walnut mixture and beat on low until combined and mixture is moist but still crumbly. Tip: Before adding the last 1/2 cup of flour mixture, squeeze tablespoon of dough to test if moist enough for a ball to form. The last 1/4 or 1/2 cup may not be necessary.
Form gently into walnut-sized balls.
Place on lined baking sheet about 1-2 inches apart.
Bake at 350 for about 12 minutes or until bottoms of cookies are light golden brown.
Cool completely and then roll in powdered sugar.