Mix together the flour, baking powder, baking soda and salt in a medium size mixing bowl then set aside.
Use a medium saucepan and place on medium heat. Place your butter in the pan and melt the butter while stirring continuously. Keep cooking until butter starts to crackle and then eventually foam.
After a couple of minutes your butter will start to form these golden specs in the bottom of the pan and it will develop a nutty aroma.
When that happened you want to continue whisking and remove from heat as soon as the butter begins to brown. Make sure to transfer immediately to a mixing bowl. Doing this will keep the butter from burning. Leave to cool until just warm enough to touch.
Then add in packed dark brown sugar and granulated sugar to cooled brown butter and whisk on medium speed with an electric hand whisk and mix it until combined.
Add in vanilla extract and eggs and then whisk to combine.
With your mixer on low you want to slowly add in the dry ingredients to the wet mix and whisk just until combined.
Fold in the chocolate chips and chunks with a wooden spoon or spatula.
Once those are folded in place your dough in the fridge for 30 minutes.
When chilling time is almost over line a large baking tray with parchment paper.
Remove the dough from the fridge. Then form 1 ½ tablespoon of dough into balls and place the lined baking sheet.
Cover with a plastic wrap and pop back into the fridge for 12-24 hours. This cooling time is mandatory to prevent cookies from over spreading.
When you ae ready to bake remove cookie dough balls from the fridge and leave at room temperature for 20 minutes.
Preheat oven to 350°F and line 2 large baking sheets with parchment paper. Place cookie dough balls on lined baking sheets, 2 inches apart.
Bake for 10-12 minutes, or until the edges begin to turn golden brown. The center may look a bit soft but cookies will continue cooking outside the oven.
Remove from the oven and leave to cool on the baking sheet for 10 mins, then transfer on to a cooling rack to cool completely.