Melt chocolate and butter

• Chop the dark chocolate and place it in a heatproof bowl with the butter.
• Melt together until smooth, then set aside to cool slightly.

Whip eggs and sugar

• Add the sugar, brown sugar, eggs and vanilla paste to a large bowl.
• Beat vigorously for several minutes to incorporate as much air as possible — this creates the thin meringue layer that gives the shiny cracked crust.

Combine wet ingredients

• Pour the melted chocolate and butter into the whipped egg mixture.
• Mix until fully combined and glossy.

Fold in dry ingredients

• Add the flour, cocoa powder and a pinch of salt.
• Gently fold with a spatula until just combined — do not overmix, or the brownies will turn out cakey.

Bake

• Pour the batter into a lined baking tin and spread evenly.
• Bake at 175°C for 25-30 minutes, until the top is shiny and cracked and a skewer comes out with a few moist crumbs.

Cool and rest

• Do not cut into the brownies straight out of the oven.
• Let them cool completely, ideally chilling them in the fridge overnight for the fudgiest texture, then slice and serve.