PREPARATION:
- Beat butter, granulated sugar and egg yolk in large bowl until light and fluffy. Blend in rum and vanilla. Stir in flour, cocoa and nuts; mix well. Cover; refrigerate until firm, about 1 hour.
- Preheat oven to 350°F. Lightly grease cookie sheets or line with parchment paper. Shape dough into 1-inch balls; place 2 inches apart on prepared cookie sheets. Bake 15 to 20 minutes or until firm. Remove to wire racks to cool. Roll in powdered sugar.
