Decadent dark chocolate brownies

Name: Decadent dark chocolate brownies
Prep time: 20 min
Cook time: 1 h 55 min
Total time: 2 h 15 min
Cuisine: American
Ingredients: 230 g unsalted butter, cut into pieces, plus extra for greasing; 70 g Dutch cocoa powder, plus extra for dusting; 440 g Rapadura sugar or raw sugar; 1 tsp baking powder; 100 g plain flour; 200 g dark chocolate (55% cocoa solids), broken into pieces; 1 pinch sea salt; 4 eggs, lightly beaten; 1 tbsp natural vanilla extract