Melt butter in a medium saucepan on medium heat and cook until browned and starting to smell nutty, about 10 minutes.
Transfer to a bowl and place in a bowl of iced water. Allow to cool, stirring occasionally.
When cooled, whip the butter over the ice until light, then discard ice.
Beat the sugars into butter until creamed.
Beat in eggs 1 at a time, beating well between each addition until light and fluffy, then beat in vanilla extract.
Set aside 1 tbsp of the flour then sift remaining flour, baking powder, bicarb and a pinch of salt together, then mix into butter mixture until a soft dough forms.
Transfer ⅓ of the dough to a separate bowl and mix in gochujang and the reserved flour, until well blended.
Fold in chocolate chips and chopped dark chocolate. Cover dough tightly with plastic wrap and refrigerate overnight.
Preheat the oven to 190°C fan forced (375°F) and line 2 large baking trays with baking paper.
Divide the dough into 24 equal portions, roughly heaped tablespoon sized.
Place cookies on trays, with at least 3cm gap between each for spreading.
Bake for 10-12 minutes, without opening the oven door. Sprinkle with a little sea salt as soon as they are out of the oven, then allow to cool for at least 15 minutes on the trays. Enjoy
