Preheat your oven to 160 degrees C (320 degrees F) on a fan setting or 170 degrees C (338 degrees F) for conventional heating. Line a baking tray with parchment paper.

In a heatproof bowl, melt the dark chocolate and butter over simmering water. Stir gently and add the vanilla extract once melted.

In a separate bowl, whisk together the caster sugar, Demerara sugar, and eggs until light and fluffy.

In another bowl, sift together the plain flour, cocoa powder, baking powder, and salt. Stir in the chocolate chips.

Gradually fold the melted chocolate mixture into the whipped egg mixture, then gently fold in the dry ingredients until just combined.

Scoop tablespoons of batter onto the prepared baking tray, leaving space between each scoop.

Bake for 12-14 minutes until the brookies are set and have a crackly top.

Remove from the oven. Optionally sprinkle a little sea salt on top for added flavor. Let cool on the tray for about 10 minutes before transferring to a cooling rack.