Preheat your oven to 175°C (350°F). Line your baking pan with parchment paper, leaving an overhang for easy removal.
In a heatproof bowl, melt the butter and dark chocolate together, either over gently simmering water or in short bursts in the microwave. Stir until smooth and glossy, then set aside to cool slightly.
In a large bowl, whisk together the sugar and eggs until the mixture is thick, pale, and slightly frothy, about 2 minutes. This develops some air in the batter for a lighter texture.
Add the vanilla extract and a pinch of flaky sea salt to the egg mixture, then gently fold in the slightly cooled chocolate mixture, creating a smooth, shiny batter.
Sift the cocoa powder and flour into the batter, then fold gently until just combined. Be careful not to overmix—the batter should be thick and velvety.
Pour the batter into your prepared pan, spreading it evenly with a spatula. Tap the pan lightly on the counter to release any trapped air bubbles and ensure a smooth surface.
Bake for 25–28 minutes, until the edges are set and a toothpick inserted into the center comes out with moist crumbs. The top should be shiny and crackled.
Remove the brownies from the oven and let them cool in the pan for about 10 minutes. Then, transfer them to a wire rack to cool completely, which helps them set and develop that perfect fudgy texture.
Once cooled, lift the brownies out of the pan using the parchment overhang. Slice into squares with a sharp knife, wiping the blade clean between cuts for neat pieces.
Sprinkle a tiny pinch of flaky sea salt on top of each brownie for that irresistible salty contrast, then serve and enjoy the rich, fudgy goodness!
