Preheat the Oven
Heat your oven to 160ºC (320ºF) with a fan, or 170ºC (338ºF) if using conventional heating. Line a baking tray with parchment paper.

Melt Chocolate and Butter
Place chopped dark chocolate and butter in a heatproof bowl. Set the bowl over a pot of simmering water, ensuring it doesn’t touch the water. Stir occasionally until melted and smooth. Add vanilla and stir to combine.

Whip Eggs and Sugars
In a separate bowl, whisk together the eggs, caster sugar, and demerara sugar on high speed using a hand mixer. Continue beating for around 5 minutes until the mixture is pale, thick, and fluffy.

Prepare the Dry Mix
Sift the flour, cocoa powder, baking powder, and salt into another bowl. Add chocolate chips and stir to combine.

Combine Wet and Dry
Gently fold the melted chocolate mixture into the whipped eggs and sugar. Then, fold in the dry ingredients with a spatula until just combined. Be careful not to overmix.

Scoop and Bake
Drop tablespoon-sized scoops of batter onto the prepared tray, spacing them apart. Bake for 12 to 14 minutes or until the tops are crackly and set.

Cool
Optionally, sprinkle with sea salt. Let the brookies cool on the tray for 10 minutes before transferring them to a wire rack to cool completely.