Cream the butter in a stand mixer or in a medium bowl with a hand mixer.
Add the sugar, flour and walnuts.
Form into a ball, and wrap in plastic wrap. Chill for 2 hours.
Preheat oven to 350°F.
Roll the chilled dough into 1 1/2-inch balls and place on a baking sheet.
Bake for 10-12 minutes, until slightly golden.
While cookies are baking add the powdered sugar to a small bowl.
Once removed from the oven, carefully roll the warm cookies in powdered sugar.
Enjoy!