PREHEAT oven to 350° F. Grease 13 x 9-inch baking pan.
MELT 1 cup morsels and butter in large, heavy-duty saucepan over low heat; stir until smooth. Remove from heat. Stir in eggs. Stir in flour, sugar, vanilla extract and baking soda. Stir in remaining morsels and nuts. Spread into prepared baking pan.
BAKE for 18 to 22 minutes or until wooden pick inserted in center comes out slightly sticky. Cool completely in pan on wire rack. Cut into bars.