PREHEAT oven to 350° F. Grease 15 x 10-inch jelly-roll pan.
COMBINE flour, cinnamon, cloves and baking soda in a small bowl. Beat butter, granulated sugar and brown sugar in a large mixer bowl until creamy. Beat in pumpkin, egg and vanilla extract until blended; gradually beat in flour mixture. Stir in 1 1/2 cup morsels and nuts. Spread into prepared jelly-roll pan.
BAKE for 18 to 22 minutes or until wooden pick inserted in center comes out clean. Cool in pan on wire rack.
PLACE remaining morsels in heavy-duty plastic bag. Microwave on MEDIUM-HIGH (70%) power for 45 seconds; knead. Microwave at additional 10- to 15-second intervals, kneading until smooth. Cut tiny corner from bag; squeeze to drizzle over bars. Cut into bars.