In a medium size bowl with a hand mixer or the bowl of a stand mixer fitted with the paddle attachment, beat the butter, 1/4 cup of the powdered sugar, and vanilla on medium speed until smooth. Add the flour and salt and beat again on medium until completely combined. Add chopped nuts and stir with a spatula until evenly dispersed. Cover bowl with plastic wrap and refrigerate at least 1 hour and up to 3 days.

When you are ready to bake the cookies, preheat the oven to 400ºF. Line a baking sheet with parchment paper or a silicone baking mat. Set aside.

Roll dough into approximately 1" balls using a cookie scoop or a Tablespoon measure. Bake until set, about 10-12 minutes. You do not want cookies to brown at all. Remove from oven and transfer cookies to wire rack. Allow to cool until you are able to handle the cookies. Roll warm cookies in remaining 1/2 cup of powdered sugar. Return cookies to wire rack and allow to cool completely. When completely cool, roll in powdered sugar again. Cookies remain fresh in an airtight container at room temperature up to 2 weeks.