Preheat oven to 350°F/180°C
In a large bowl, combine flour, cocoa powder, baking soda, espresso powder and salt and whisk to combine
Using a separate bowl (or bowl of a stand mixer), place the butter and brown sugar
Beat on medium high until light and fluffy
Add eggs, one at a time, and mix to fully incorporate before adding the next egg
Add the orange zest, hazelnut liqueur and orange liqueur
Mix well and scrape down the sides of the bowl
With the mixer on low, add one third of the flour-cocoa powder mixture
Mix until fully incorporated, then scrape the sides of the bowl
Repeat two more times with the remaining two thirds of dry ingredients
Scrape the sides of the bowl and mix until no white streaks are present.
Add the hazelnut pieces and using a rubber spatula, fold in by hand.
Divide the dough into two roughly equal portions
Line a baking sheet with parchment paper
On the baking sheet roughly shape each portion of dough into a 12” long log. Flatten the log to about 2 ½” wide .
Place the cookie sheet in the in middle of oven and bake for 30 - 35 minutes, or until the surface is lightly cracked
Cool logs on the sheet pan on a rack 10 - 15 minutes and transfer to a cutting board.
With a serrated knife cut logs crosswise into 1/2-inch thick slices.
Arrange slices, cut sides down, on 2 baking sheets
Return biscotti to oven and bake an additional 12 to 15 minutes, or until golden and crisp.
Transfer biscotti to racks and cool.