Heat about 2 inches of water in a saucepan. Once simmering, reduce the heat to medium low and add a heat-proof mixing bowl on top (placing it carefully so that the base is not touching the water). Add the chopped chocolate and butter, stirring regularly until melted and smooth. Remove from heat and set aside the bowl so that the melted chocolate can cool down.
Pre-heat the oven to 180°C. Line a 6 inch square tin lined with baking paper and grease well.
Then add the condensed milk and beat for 5 minutes using a hand whisk or electric mixer
Sift the flour, baking powder and cocoa powder in a separate bowl. Give it a good whisk to make sure it is well-combined.
Now fold in the sieved dry ingredients (flour, baking powder and cocoa powder) into the chocolate mixture until there are no lumps. Don’t over-mix.
Pour into the baking tin and let this sit outside for 5-7 minutes. Optional: sprinkle on some sea salt!
Bake the brownies for 20 minutes (or so) until a toothpick emerges mostly clean (with a few fudgy crumbs attached).
Let the brownies cool down completely before slicing.