In a bowl with a hand mixer or a bowl of a stand mixer with the paddle attachment, cream the butter. Add the sugar and mix until it is light and fluffy.
Add the flour, salt, vanilla, and chopped walnuts or pecans. Mix until combined. Make sure to scrape the sides occasionally to get all the ingredients incorporated.
Turn the dough onto the counter top and loosely use your hands to bring the dough together into a ball. Cover with plastic wrap and place it in the refrigerator for 30 minutes.
When ready to bake, remove the cookie dough from the refrigerator. Preheat your oven to 350 °F (177 °C) and line two baking trays with parchment paper.
With a cookie scoop, scoop dough and roll firmly into a ball of dough. Place on the baking tray.
Bake for 25 - 30 minutes until slightly golden.
Remove from the oven and let them cool for two to three minutes. Roll them in the powdered sugar until completely covered and set on a rack to cool completely.
If you want them really white, roll them in the sugar for a second coating once they are completely cool.