Decadent dark chocolate brownies

Name: Decadent dark chocolate brownies
Prep time: 10 min
Cook time: 1 h 30 min
Total time: 1 h 40 min
Cuisine: American
Ingredients: 290 g unsalted butter, cut ino pieces, plus extra to grease; 550 g Rapadura sugar or raw sugar; 1 ¼ tsp baking powder; 90 g Dutch cocoa powder, plus extra to dust; 125 g plain flour; 250 g dark chocolate (55% cocoa solids), broken into pieces; 1 pinch sea salt; 5 eggs, lightly beaten; 5 tsp natural vanilla extract