Heat oven to 350°F. Place nuts on a baking sheet and cook for 7 to 10 minutes, until slightly darker in appearance and fragrant. Remove from the oven and cool completely.

In a food processor, grind nuts, pulsing several times, until powdery but stop before the nuts begin to clump.

To make cookie dough with a hand mixer or stand mixer: In a large bowl, beat room temperature butter with vanilla and 1/2 cup of the powdered sugar until light and fluffy. Add flour, salt, and ground nuts and beat until smooth. Cover bowl with plastic wrap and chill in the fridge for 30 minutes to 1 hour, until firm.

To make cookie dough in a food processor: Once you’ve ground your nuts to a powdery texture, add 1/2 cup of the powdered sugar, salt, and flour to the work bowl and blend to combine. Cut butter into chunks and add to the food processor along with vanilla. Run the machine until butter is fully blended into the other ingredients, scraping down the work bowl as needed to mix evenly. Transfer to a bowl and cover it with plastic wrap. Chill bowl in fridge for 30 minutes to 1 hour, until firm.

Heat oven again to 350°F. Scoop dough in 1-tablespoon measures and roll between palms into balls. Arrange balls on a parchment-lined baking sheet, spacing 1 inch apart. Bake cookies until golden brown on bottom and just pale golden and dry to the touch on top, about 14 to 16 minutes. Cool cookies for 5 minutes on baking sheet.

While cookies bake, sift the remaining 1 cup powdered sugar into a low wide bowl, along with cinnamon, if using. After cookies have cooled for 5 minutes, gently toss warm cookies in sugar, rolling them over to coat. Transfer coated cookies to rack and cool completely. Repeat procedure with the remaining dough.