Step 1

Place 2 sticks unsalted butter in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Let sit at room temperature until the butter is softened. Meanwhile, place 1 cup walnuts in a large frying pan and cook over medium heat, stirring frequently, until fragrant and lightly browned, 4 to 6 minutes. Transfer to a cutting board and let cool completely, about 20 minutes. Finely chop the nuts.

Step 2

Place the walnuts and 2 cups all-purpose flour in a medium bowl and stir to combine.

Step 3

Add 1/2 cup of the powdered sugar, 2 teaspoons vanilla extract, and 1/4 teaspoon kosher salt to the bowl of butter. Beat with the paddle attachment, starting on low speed and gradually increasing to medium-high speed, until light and fluffy, 2 to 3 minutes. Gradually add the flour mixture and beat on low speed until just combined.

Step 4

Transfer the dough to a sheet of plastic wrap, form it into a 1-inch-thick disc, and wrap completely in the plastic. Refrigerate until firm but still soft enough to scoop, 30 to 45 minutes.

Step 5

Arrange 2 oven racks to divide the oven into thirds and heat the oven to 350℉. Line 2 rimmed baking sheets with parchment paper or silicone baking mats. Place the remaining 1 cup powdered sugar in a shallow bowl or pie plate.

Step 6

Scoop the dough out into level 1-tablespoon portions (34 to 36). Roll into balls. Place the dough balls at least 2 inches apart on the baking sheets, 15 to 20 per sheet.

Step 7

Bake for 8 minutes. Rotate the baking sheets between racks and from front to back. Bake until the tops of the cookies are set and edges are golden-brown, 7 to 8 minutes more.

Step 8

Let the cookies cool on the baking sheets for 10 minutes. While still warm, gently drop each cookie into the powdered sugar and flip to coat completely. Place in a single layer on a wire rack; reserve the remaining powdered sugar. Let cool completely, about 15 minutes more. Coat again in the powdered sugar.