Preheat oven to 325°. Grease 13 x 9-inch baking pan; set aside.
Combine flour, cocoa powder, baking soda and salt in medium bowl; set aside.
Beat Country Crock® Buttery Sticks and oil in another medium bowl with electric mixer until light and fluffy. Add sugar and eggs, one at a time, beating well after each addition. Blend in vanilla. Alternately blend in flour mixture and buttermilk, beating well after each addition. Stir in zucchini.
Evenly pour mixture into prepared pan, then sprinkle with chips and walnuts. Bake 60 minutes or until toothpick inserted in center of cake comes out clean. Cool 10 minutes on wire rack; remove from pan and cool completely. Cut into squares and serve.