Prepare the pan and oven

• Line a square cake pan with parchment paper.
• Preheat the oven to 175 °C.

Melt the chocolate and butter

• Melt the chopped dark chocolate with the butter in a saucepan over low heat until smooth.
• Let the mixture cool slightly.

Whisk the sugars and eggs

• Whisk the granulated sugar, brown sugar and eggs vigorously until pale and thickened.
• Whisking well is what creates the shiny crackly top.

Combine the wet mixtures

• Pour the slightly cooled chocolate and butter into the egg mixture.
• Whisk until fully combined and glossy.

Fold in the dry ingredients

• Add the sifted flour, cocoa powder and salt.
• Fold gently with a spatula just until no dry streaks remain, without overmixing.

Bake the brownies

• Pour the batter into the lined pan and spread evenly.
• Bake until the edges are set and the center is slightly soft.

Cool and cut

• Let the brownies cool completely in the pan so the crackly top sets.
• Cut into squares and serve.