Step 1: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
Step 2: In a large mixing bowl, cream together the softened unsalted butter and 1/2 cup of powdered sugar until light and fluffy, about 2-3 minutes.
Step 3: Beat in the vanilla extract and salt until just combined.
Step 4: Gradually add the all-purpose flour to the butter mixture, mixing on low speed until a soft dough forms. Fold in the finely chopped pecans (or walnuts) until evenly distributed.
Step 5: For best results, cover the dough and chill it in the refrigerator for at least 30 minutes. This helps prevent spreading during baking.
Step 6: Roll the chilled dough into 1-inch balls and place them about 1 inch apart on your prepared baking sheet.
Step 7: Bake for 12-15 minutes, or until the edges are very lightly golden and the bottoms are just set. Do not overbake; cookies should still look pale on top.
Step 8: As soon as the cookies come out of the oven, while they are still warm, gently roll them in additional powdered sugar.
Step 9: Transfer the sugar-coated cookies to a wire rack to cool completely. Once fully cooled, roll them in powdered sugar a second time to achieve that thick, snowy coating.