Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.
Cream together butter and confectioners' sugar until smooth. Stir in vanilla. Mix in the flour, and then one cup of the chocolate chips. Shape dough into 2x1/2 inch logs. Place logs 2 inches apart on prepared cookie sheets.
Bake for 10 to 13 minutes in preheated oven, or until firm. Let cookies cool completely before removing from pan (shortbread is brittle).
Melt the remaining 1 cup chocolate chips and shortening over a double boiler, stirring frequently until smooth. Dip one end of each cookie into the chocolate, then into the nuts. Place onto waxed paper until set.