1. Heat oven to 350°F. Line 15-1/2x10-1/2x1-inch jelly-roll pan with foil; grease foil.
2. Stir together flour, cocoa, baking soda and salt. Beat butter, granulated sugar blend, brown sugar blend and vanilla in large bowl until well blended. Add eggs; beat well. Gradually add flour mixture, beating well. Stir in chocolate chips and walnuts. Spread and press dough in prepared pan.
3. Bake 15 to 17 minutes or until edges start to pull from edges of pan and center springs back when touched lightly. Cool completely in pan on wire rack. Using edges of foil, lift cookie from pan. Place on cutting board; cut into bars. 48 bars.