1 Toast the nuts on the stovetop: Place the nuts in a medium skillet and place over medium heat. Toast the nuts, stirring frequently, until they darken slightly and smell fragrant and nutty, about 5 minutes.
Remove the pan from heat and let the nuts cool in the pan.
2 Crush the nuts: Once the toasted nuts are warm to the touch, but not hot, pour them into a quart-size sealable freezer bag. Seal the bag, and then use a rolling pin to roll and crush the nuts until they are crushed into a chunky powder. Set aside until needed.
(Alternatively, pulse in a food processor until powdery. Be careful of over-processing or the nuts will turn into nut butter!)
3 Mix the butter and sugar: Place the butter and powdered sugar in the bowl of stand mixer fitted with a paddle attachment. Beat together on medium speed until the sugar is absorbed into the butter and the buttery paste clings to the side of the bowl. Add the vanilla and beat for an additional 30 seconds to incorporate.
4 Add the flour and salt: Mix on low speed. As the dry ingredients start to absorb into the butter-sugar mixture, you can increase the speed back to medium. Once all the flour is mixed in and a dough has formed, stop the mixer.
5 Empty the crushed nuts into the bowl with the dough: Mix on low speed to incorporate.
6 Chill the dough: Scrape the dough onto a piece of plastic wrap and flatten into a disk about 1-inch thick. Wrap tightly with the plastic wrap and place in the refrigerator for at least 1 hour or until the dough is firm.
7 About 10 minutes before you’re ready to bake, preheat the oven to 350F. Line 2 baking sheet with parchment paper or a silicon baking mat.
8 Remove the chilled dough out of the refrigerator and form into 1-inch balls of dough. (If your dough chilled longer than 1 hour, you may need to let it soften for a few minutes at room temperature.) Roll the balls of dough in powdered sugar and place on the baking mat, spaced slightly apart.
9 Bake for 17 to 19 minutes, or until the cookies start to brown slightly on top and are golden brown on the bottoms. Let the cookies cool on the baking sheet for 10 minutes after baking.
10 While the cookies are still warm, roll each cookie in the powdered sugar again. Return the cookies to the cooling rack and let cool completely before serving.
Store at room temperature in an airtight container. They will keep well for at least a week.