Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, mix the butter, granulated sugar and brown sugar until fully combined. Add the eggs and mix to combine. Add the flour, cocoa powder, baking soda and salt and mix. Add the pecans and both chocolate chips; mix until just combined.
Drop heaping tablespoons of dough onto the baking sheets. Bake, rotating the sheets once halfway through, until the cookies are set, about 12 minutes. Transfer to a rack to cool. Repeat with the remaining dough.