Preheat oven to 350°F. Line a large baking sheet with parchment paper.
Whisk or sift together flour, cocoa powder, baking soda, and salt.
In a mixing bowl, using an electric mixer, beat together oil and sugar. Add eggs and beat until combined, then beat in the vanilla and coffee powder (or extract).
Stir in flour mixture to form a stiff dough. Stir in nuts and chocolate chips.
Turn dough out onto baking sheet and divide it into 2 equal parts.
Dampen hands with a little water and form each dough halve into a 12x2 inch log, leaving at least 5 inches of space between the logs.
Bake logs for 30 or until slightly firm to the touch. Cool biscotti on baking sheet for about 5 minutes.
Reduce oven heat to 300 degrees F.
On a cutting board cut biscotti diagonally (cut straight down, don't saw) and stand it on the baking sheet so that both sides are exposed. Bake for about 12-15 minutes or until it starts to feel a little dry to the touch. Let cool completely. It will crisp up a little more as it cools.