Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone mats. Set aside.

In a medium bowl, whisk together the flour, salt, and the chopped nuts. Set this dry mixture aside.

In a separate large bowl, using an electric mixer (stand mixer fitted with the paddle attachment is ideal), beat the softened butter until creamy. Add the 1/2 cup of confectioners' sugar (for the dough) and the vanilla extract. Beat until the mixture is light and fluffy, scraping down the sides of the bowl as needed.

Reduce the mixer speed to low. Gradually add the reserved dry ingredient mixture to the wet mixture. Mix only until the dough just comes together and a cohesive ball forms. Do not overmix. The dough will be stiff but should hold its shape when pressed.

Scoop or roll rounded teaspoons of dough into uniform balls, approximately 1 inch in diameter. Place the dough balls about 1 inch apart on the prepared baking sheets.

Bake for 12 to 15 minutes, or until the bottoms are lightly golden and the cookies are set. They should remain pale on the top.

First Sugar Roll (Crucial): While the cookies are still hot, place about 1 cup of the reserved coating confectioners' sugar in a shallow bowl. One by one, gently roll the hot cookies completely in the powdered sugar until fully coated. Transfer the cookies to a wire rack to cool completely.

Second Sugar Roll (The 'Snowball' Effect): Once the cookies are completely cool (this may take 30–60 minutes), roll each cookie one more time in the remaining powdered sugar. This final roll ensures a thick, opaque white coating.