PREHEAT oven to 375° F. Grease 9-inch-square baking pan.
COMBINE flour, baking soda and salt in small bowl. Beat sugar, butter and vanilla extract in large mixer bowl until creamy. Beat in egg; gradually beat in flour mixture. Stir in 1 1/4 cups morsels and nuts. Spread into prepared baking pan.
BAKE for 20 to 23 minutes. Remove pan to wire rack. Sprinkle with remaining morsels. Let stand for 5 minutes or until morsels are shiny; spread evenly. Cool completely in pan on wire rack. Refrigerate for 5 to 10 minutes or until chocolate is set. Cut into bars.