Preparation

• Preheat the Oven: Set your oven to 160ºC (320ºF) with a fan or 170ºC (338ºF) for conventional heating. Prepare a baking tray by lining it with parchment paper.
• Melt Chocolate and Butter: In a heatproof bowl, combine the chopped dark chocolate and butter. Place this bowl over a pan of simmering water, ensuring the bottom of the bowl does not touch the water. Stir until fully melted and combined. Stir in the vanilla extract.
• Whip Eggs and Sugars: In another bowl, use an electric hand whisk to beat the caster sugar, demerara sugar, and eggs until very light, thick, and fluffy, about 5 minutes.
• Combine Dry Ingredients: Sift together the flour, cocoa powder, baking powder, and salt in a bowl, then add the chocolate chips.
• Integrate Chocolate Mixture: Gradually fold the melted chocolate and butter mixture into the whipped eggs and sugars.
• Fold in Dry Ingredients: Carefully fold the dry ingredients into the wet mixture using a spatula until just combined.
• Bake the Brookies: Scoop tablespoons of batter onto the prepared baking tray and bake for 12-14 minutes.
• Cool and Finish: Remove from the oven, sprinkle with sea salt if desired, and let them cool for about 10 minutes before transferring to a cooling rack.