Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.
In a large bowl, cream together the softened butter, granulated sugar, and brown sugar until smooth.
Beat in the eggs one at a time, then add vanilla extract.
In a separate bowl, whisk together the flour, cocoa powder, baking soda, and salt.
Gradually mix the dry ingredients into the wet ingredients until fully combined.
Fold in the chocolate chunks and chopped pecans.
Drop spoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake for 9–10 minutes, or until the edges are set. The centers may look slightly soft—this is perfect.
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.