Preheat oven to 350 degrees F (180 degrees C). Grease and lightly flour cookie sheet.
In a small bowl, mix flour, baking powder and salt.
Beat butter and sugar in large bowl until light and fluffy. Beat in eggs and vanilla. Gradually add flour mixture, beating well after each addition. Stir in chocolate and nuts.
Divide dough into two equal parts. On floured surface, shape dough into two logs, 14 inches long, 1-1/2 inches wide and 1 inch thick. Place two inches apart on prepared cookie sheet.
Bake for 25 minutes or until lightly browned. Remove to a cutting board. Let cool 5 minutes. Cut into 3/4 inch thick diagonal slices and return to cookie sheet, standing upright.
Bake 10 minutes more or until slightly dry. Cool completely on wire racks.
