Preheat your oven to 175°C (350°F) and line your baking pan with parchment paper, ensuring it overhangs for easy removal.
In a saucepan over low heat, melt the butter and dark chocolate together, stirring gently until the mixture is smooth and glossy, filling your kitchen with a rich chocolate aroma.
Remove the saucepan from heat and let the mixture cool slightly while you prepare the eggs and sugar.
In a large bowl, whisk the eggs and sugar together until the mixture becomes pale, slightly thickened, and you hear a gentle whisking sound—this aerates the batter.
Pour the slightly cooled chocolate mixture into the egg and sugar mixture, stirring gently with a spatula until fully combined and smooth.
Gradually fold in the sifted flour and a pinch of sea salt, mixing just until no streaks remain—be careful not to overmix to keep the brownies tender.
Add the vanilla extract and fold it into the batter, which should now be thick, shiny, and smooth, with a gentle ripple when lifted with the spatula.
Pour the batter into your prepared pan, spreading it evenly with the spatula to ensure a uniform thickness.
Bake for 20–25 minutes, or until the edges are set and pull away slightly from the pan, while the center remains slightly gooey when gently shaken.
Remove the brownies from the oven and let them cool in the pan for about 15 minutes, allowing the center to firm up slightly.
Transfer the brownies to a wire rack using the parchment overhang, letting them cool completely for clean slicing.
Once cooled, cut into squares and serve slightly warm or at room temperature, enjoying the rich, fudgy texture and shiny crackly top.
