Preheat oven to 350°F. Line a cookie sheet with parchment paper.

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

In a stand mixer bowl, beat together butter and granulated sugar until light and fluffy. Add vanilla and eggs; beat until combined. Stir in flour mixture to form a stiff dough. Stir nuts and chocolate chips.

Wet hands and form dough into two slightly flattened logs, each 12 inches long and 2 inches wide. I do this directly on the baking sheet.

Sprinkle cinnamon sugar mixture over logs, coating them evenly. Bake logs 35 minutes, or until slightly firm to the touch. Cool on baking sheet 5 minutes.

On a cutting board, cut biscotti diagonally into ¾-inch slices. Arrange cut sides down, on baking sheet and bake until crisp around edges, about 10-20 minutes. Biscotti will crisp up more as it cool, so be careful not to overbake

Let cool on a rack.