1. Adjust racks to the middle of the oven.

2. Cream the butter and 1/2 cup of the confectioners' sugar until well blended. Beat in the egg yolk. Add the vanilla extract, or slit the vanilla bean and scrape the seeds into the mixture.

3. With the mixer on low to medium-low speed, beat in the flour and salt until the mixture is thoroughly blended. Then add the walnuts and if necessary, do the final mixing with your hands.

4. Chill the dough in the freezer for 30 minutes so it will be manageable. Meanwhile, preheat the oven to 400 degrees. Shape the dough into 1-inch balls and place them 2 inches apart on ungreased cookie sheets. Bake only until set, 9 to 10 minutes. Do not let the cookies brown.

5. While they are still warm, roll the cookies in the remaining 3/4 cup confectioners' sugar. Let cool and roll again. Package well and store in the refrigerator or freezer. To serve, let return to room temperature.