Preheat oven to 350-degrees F. Prepare large baking sheet by lining with parchment, baking mat, or with butter and flour

In a bowl whisk together flour, cocoa powder, baking soda, and salt

In a separate bowl, using an electric mixer beat together butter and granulated sugar until light and fluffy. Add eggs and beat until combined well. Add vanilla extract and combine well

Stir in flour mixture to form a stiff dough. Mix in chocolate chips until combined

Divide dough in half. Flour hands and form dough into two slightly flattened logs on prepared baking sheets, each approximately 12 inches long and 2 inches wide. Sprinkle with confectioners’ sugar

Bake 30-35 minutes, or until slightly firm to the touch. Cool on baking sheet 5 minutes

Transfer to cutting board and cut diagonally into ¾-inch slices. Arrange biscotti, cut sides down, on baking sheet and bake for about 10 minutes, or until crisp. Cool on rack