Double Chocolate Walnut Biscotti
["2 cups all-purpose flour", "1/2 cup unsweetened cocoa powder", "1 tsp. Baking soda", "1 tsp. salt", "3/4 stick (6 Tbsp.) unsalted butter, softened", "1 cup granulated sugar", "2 large eggs", "1 cup walnuts, chopped", "3/4 cup semisweet chocolate chips", "1 Tbsp. Confectioners sugar"]
["Preheat oven to 350\u00b0.", "Butter and flour a large baking sheet.", "In a bowl, whisk together flour, cocoa powder, baking soda and salt.", "In another bowl with an electric mixer, beat together butter and granulated sugar until light and fluffy.", "Add eggs and beat until combined well.", "Stir in flour mixture to form a stiff dough.", "Stir in walnuts and chocolate chips."]
["flour", "cocoa", "Baking soda", "salt", "unsalted butter", "sugar", "eggs", "walnuts", "semisweet chocolate chips", "Confectioners sugar"]