Preheat the oven to 325°F. Line 2 baking sheets with parchment paper or lightly grease them.
In a large mixing bowl, beat together the butter, sugar, vanilla extract and salt.
Beat in the almond flour and the all purpose flour.
Scoop about a teaspoon of dough and roll them into balls. Place the balls on the prepared baking sheet, about 1" between them.
Bake the cookies for 15~20 minutes or until they feel set on top. They should be lightly browned.
Put confectioners sugar in a shallow bowl.
Remove the cookies from the oven and allow them to cool on the pan for a few minutes. Transfer 4~5 cookies at a time and roll them in the sugar to coat. Transfer them to a rack to cool.
When the cookies are cool, roll them again in the sugar - they should be generously coated and snowy white.
Store in an airtight container at room temperature for up to a week. Freeze for longer storage.