Preheat oven to 350 ° F
In a food processor, pulse nuts until fine. If you don't have a food processor, chop on a cutting board. Set aside
Beat together sugar and butter until creamy. Use a hand mixer or beat by hand. Beat in egg and vanilla until uniform and creamy.
Sift the salt into the flour, and then, one cup at a time, add the flour to the butter mixture and stir by hand. Take your time and let the flour absorb the butter. Add the rest of the flour and continue to mix by hand until uniform. Fold in the nuts. Again, take your time. The dough may seem a bit dry at first, but given a few minutes, the flour will absorb the butter and will make a smooth dough.
Line a cookie tray with parchment paper or grease with butter. Roll the dough into small balls, about 2/3 inch or 1 heaping teaspoon (20 grams per cookie if using a scale). Place the balls on the cookie tray and bake for 20 minutes until light brown. It will make about 50 cookies.
Remove cookies from oven and cool until warm. Put the powdered sugar in a bowl and a few at a time, roll the cookies around to coat completely.
Serve right away or store in an airtight container for up to a week.