Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a bowl, whisk together the flour, cocoa powder, baking soda, and salt.
In another bowl, beat the butter and sugar together until light and fluffy. Add the eggs one at a time, then mix in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, mixing until combined. Stir in the chocolate chips.
Divide the dough in half and shape each half into a log about 12 inches long and 2 inches wide. Place the logs on the prepared baking sheet.
Bake for 25 minutes, then remove from the oven and let cool for 10 minutes. Reduce the oven temperature to 325°F (165°C).
Using a serrated knife, cut the logs into ½-inch slices. Arrange the slices cut side down on the baking sheet and bake for another 10 minutes. Flip the slices and bake for an additional 10 minutes, or until crisp.
Let the biscotti cool completely on a wire rack before serving.