PREHEAT oven to 350° F. Grease 13 x 9-inch baking pan.
MELT 1 cup morsels and butter in medium, heavy-duty saucepan over low heat. When morsels and butter begin to melt, remove from heat; stir. Return to heat for a few seconds at a time, stirring just until mixture is 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 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.