PREHEAT oven to 375° F.
BEAT butter, sugar, vanilla extract and salt in large mixer bowl. Gradually beat in flour. Stir in 1 1/2 cups morsels and nuts. Press into ungreased 15 x 10-inch jelly-roll pan.
BAKE for 20 to 25 minutes or until golden brown and set. Cool until just slightly warm.
MICROWAVE remaining 1/2 cup morsels in small, heavy-duty plastic bag on HIGH (100%) power for 30 to 45 seconds; knead. Microwave at additional 10- to 15-second intervals, kneading until smooth. Cut tiny corner from bag; squeeze to drizzle over cookie. Allow chocolate to cool and set; break cookie into irregular pieces.
NOTE: Including nuts helps keep these cookies moist.