Line 2 baking sheets with parchment paper and preheat the oven to 180°C/350°F.
Cream together the room temperature butter and sugar until light and fluffy.
I use my stand mixer but you can use a hand mixer and large bowl too.
Scrape down the bowl with a spatula then add the eggs, beating well after each addition. Stir in the vanilla.
Sift together the flour, cocoa powder, baking powder, baking soda and a teaspoon salt.
Add the dry ingredients to the wet ingredients. Beat until just combined then add the pecan nuts and chocolate chunks.
Using an ice cream or cookie scoop, scoop the dough and place on the prepared cookie sheets.
Space the cookies a few centimeters apart as they will spread while baking. Place in the fridge and allow to chill for 30 minutes.
Place the cookie sheets in the oven and allow to bake for 7-10 minutes until the edges are crisp but the center of the cookies are still a little soft.
Remove from the oven and allow to cool for 5 minutes on the pans then transfer to wire racks and allow to cool.
I like finishing the cookies with a sprinkle of flaky sea salt but that is optional.