Grind the nuts in a manual nut grinder, if you have one or carefully in the food processor.
Beat the butter with an electric mixer until smooth and creamy. Add sugar, salt and vanilla and beat for 1 or 2 minutes until smooth and fluffy. With a wooden spoon stir in the nuts, then stir in the flour until the dough gather into a mass. Knead the dough briefly in the bowl until it comes together.
Prepare the baking sheet by lining with non-stick baking paper and preheat the oven to 180C/350F
Divide the dough into 36 equal parts. Roll each into a ball and place 1 to 2 inches apart on the prepared sheet.
Bake until the cookies are a very pale golden brown all over 20-25 minutes. This was way too long for my oven and I removed them from the oven before 15 minutes was up. Next time I think I would lower the temperature to allow them to bake for the entire allocated time.
Sift the confectioners' sugar into a large plastic bag and add half the hot cookies. Twist the top of the bag and gently manipulate the bag to coast the hot cookies with a generous layer of sugar. Remove the cookies from the bag with a slotted spoon and set on wire racks to cool. Repeat with the remaining cookies while they are hot.
I found the cookies were a bit soft to use the plastic bag method so a transferred the confectioners' sugar to a bowl and coated the cookies in the bowl. I have to say I always have trouble when I coat hot cookies because the sugar seems to absorb a lot of moisture and become sticky so I then sprinkle a little bit more on top as they cool. I think the humidity in our area doesn't help.