Preheat oven to 350ºF
In a medium bowl, whisk together dry ingredients flour, cocoa powder, baking soda, and salt.
In another bowl with an electric mixer beat together butter and granulated sugar
until light and fluffy.
In a large bowl, add eggs and beat until combined well. Stir in the flour mixture to form a stiff dough.
Fold in walnuts and chocolate chips.
Place parchment paper on a baking sheet. And with floured hands and a lightly floured surface, form dough into two slightly flattened log shape, each 12 inches long and 2 inches wide logs. Place them on your prepared baking sheet and sprinkle them with confectioner sugar.
For the first bake, bake logs for 35 minutes, or until slightly firm to the touch.
Cool biscotti on a baking sheet for 5 minutes. On a cutting board, using a sharp knife, cut biscotti diagonally into 3/4-inch slices.
For the second bake, place slices of biscotti, cut sides down, on the baking sheet, and bake until crisp, about 10 minutes.
Let cool on a wire rack until completely cooled.