1. cream the butter with half the powdered sugar and the vanilla in a large bowl. sift the flour and salt together into the bowl and fold together. Cover and let chill for 1 hour, or until firm.
2. preheat the oven to 375. with floured hands, shape the dough into 1 inch balls and place about 1 1/2 inches apart on 2 large baking sheets
3. Bake for 10 minutes or until set but not browned, rotating the sheets so that the cookies bake evenly. let cool on the baking sheets for 2-3 minutes.
4. Place the remaining powdered sugar in a shallow dish or pie plate. Roll the warm cookies in the sugar, then let cool on wire racks for 30 minutes. When cool, roll again in the sugar. store in airtight containers.