Preheat the oven to 325 degrees F and line two baking sheets with parchment paper or with baking mats.
In a food processor, process 1 cup of nuts until the texture is similar to coarse cornmeal, about 15 seconds of processing. Place the finely chopped nuts in a medium bowl.
Add the second cup of nuts to the food processor and pulse until coarsely chopped, about 5 seconds. Add these to the finely chopped nuts in the bowl.
Add the flour and salt to the bowl, and stir to combine.
In a medium bowl (or in the bowl of a stand mixer), beat together the butter and the granulated sugar on medium speed until the mixture is light and fluffy, about 3 minutes.
Add the vanilla, and stir to combine.
Slowly add the flour-nut mixture, and stir until it is combined and forms a soft dough, about 30 seconds. Make sure no dry pockets remain in the dough.
Roll 1 tablespoon of dough into a round ball, and place them 1 inch apart on the prepared baking sheet. Repeat with remaining dough.
Bake until the tops are pale golden and the bottoms are just starting to brown, about 18 minutes.
Let the cookies rest on the cookie sheet for 2 minutes, and then place them on a wire rack to cool completely.
Place the powdered sugar in a shallow dish, and roll each cookie in it to coat the outside evenly. Gently shake off any excess sugar and serve.
Store extra cookies in an airtight container for up to 2 days or in the freezer for up to 6 weeks.
Notes
If you aren't serving the cookies immediately, you'll want to re-roll them in powdered sugar just before serving to ensure they are evenly covered. (Sometimes, the sugar absorbs or shakes off the cookies.)
I prefer pecans for this recipe, but I almost always prefer pecans over walnuts. Use whatever nuts you love or have on hand.
This is a super easy and fun recipe to make with kids. Let them roll the dough into balls and dredge in the powdered sugar!
If using salted butter, cut back on the amount of salt called for in the recipe. Just taste a bit of the dough to see if it needs a pinch more salt or if the salted butter has made it salty enough for your taste.