01 -
Set your oven to 160ºC (320ºF) with a fan or 170ºC (338ºF) for conventional heating. Line a baking tray with parchment paper.
02 -
In a heatproof bowl, combine the chopped dark chocolate and butter. Place over a pan of simmering water, ensuring the bowl does not touch the water. Stir occasionally until melted and smooth. Stir in vanilla extract.
03 -
In a medium bowl, use an electric hand whisk on high speed to beat the eggs, caster sugar, and demerara sugar until very light, thick, and fluffy.
04 -
Sift together the flour, cocoa powder, baking powder, chocolate chips, and salt in a separate bowl to ensure even mixing and no lumps.
05 -
Gradually fold the melted chocolate and butter mixture into the whipped eggs and sugars, stirring gently to maintain the mixture's airiness.
06 -
Fold the dry ingredients into the wet ingredients carefully using a spatula, mixing only until just combined.
07 -
Scoop tablespoons of batter onto the prepared baking tray, spaced apart to allow for spreading. Bake for 12-14 minutes until set and crackly on top.
08 -
Remove from the oven and sprinkle with sea salt, if desired. Cool on the baking tray for 10 minutes before transferring to a cooling rack.