In a medium bowl whisk together the flour, cocoa powder, baking powder, baking soda and salt.
In a separate bowl beat together the butter, brown sugar and granulated sugar until smooth.
Mix in the melted dark chocolate
Then mix in the egg and vanilla extract.
Add the flour mixture into the butter mixture. Start with the mixer on a low speed, and gradually mix together until combined.
Turn off the mixer and stir in 1 1/4 cup chocolate chips.
Cover the bowl with plastic and place in the fridge to chill for at least 3 hours or up to 48 hours.
Once ready to bake, preheat the oven to 350F (180C of 170C fan forced) degrees. Line 2 cookie sheets with parchment paper or a silicone baking mat.
Take the dough out of the fridge. If it's been in the fridge overnight, let it sit on the counter for about 10 minutes first. Then form the dough into balls with about 3-4 tablespoons of dough each (about 1/4 cup or a little less.
Place the dough balls 3 inches apart on the lined cookie sheets. Bake 1 sheet at a time in the middle of the oven for 12-14 minutes, or until the tops look just set.
Remove from the oven. Place a few extra chocolate chips on top of each cookie with the 1/4 cup you reserved. Cool the cookies on the tray for at least 10 minutes, then transfer to a wire rack to continue cooling.