Preheat oven to 350°F. Mix flour, cocoa powder, baking soda and salt in medium bowl. Set aside. Beat butter and sugars in large bowl with electric mixer on medium speed until light and fluffy. Add eggs and extract; mix well. Gradually beat in flour mixture on low speed until well mixed. Stir in chocolate chips and walnuts.
Drop by rounded tablespoons about 2 inches apart onto baking sheets sprayed with no stick cooking spray.
Bake 8 to 10 minutes or just until cookies are set. Cool on baking sheets 2 minutes. Remove to wire racks; cool completely.