1. MELT chocolate & butterscotch morsels with sweetened condensed milk in top of double boiler over hot (not boiling) water. Stir occasionally till morsels melt and mixture begins to thicken. Remove from heat; add chopped walnuts and vanilla. Blend well. Chill for about 1 hour till mixture thickens. Line bottom of 9″ pie pan with a 12″ square of foil. Place cup walnut halves in bottom of pan, forming a 2″ wide flat ring.