In a large bowl, whisk together the all-purpose flour, chopped pecans (or walnuts), and salt. Set aside.

Using a stand mixer with the paddle attachment (or a large bowl with an electric handheld mixer), beat the softened unsalted butter on high speed for 1-2 minutes until soft, fluffy, and creamy. Scrape down the sides of the bowl.

Add 1 cup of confectioners' sugar and vanilla extract to the butter. Beat on low speed to combine, then increase to high speed and beat until the mixture is soft and fluffy. Scrape down the sides of the bowl.

Gradually add the dry ingredients mixture (flour, nuts, salt) to the wet ingredients. Mix on low speed until just combined; be careful not to overmix.

Using a 1-tablespoon cookie scoop, form about 24 equally sized mounds of dough. Place them on a large plate, cover with plastic wrap, and refrigerate for at least 30 minutes (up to 3 days). Do not chill the entire bowl of dough, as it will become too crumbly.

While the dough chills, preheat your oven to 400°F (200°C). Line two baking sheets with parchment paper or silicone baking mats.

Arrange the chilled cookie dough mounds on the prepared baking sheets, leaving some space between them (they don't spread much). Bake one sheet at a time on the center rack for best results.

Bake at 400°F (200°C) for 7-10 minutes, or at 375°F (190°C) for 10-15 minutes. Watch carefully, baking until the bottoms are barely golden browned and the tops are set. Cookies will firm up more as they cool.

Let the cookies cool on the baking sheet for about 10 minutes before rolling them in confectioners' sugar.

Place a generous amount (at least 1 cup) of confectioners' sugar in a small bowl. Roll each warm cookie through the sugar until fully coated. Repeat for all cookies.

For a more 'snow-covered' look and extra sweetness, it is recommended to roll the cookies through additional confectioners' sugar a second time after they have cooled slightly more.