Preheat & Prep – Preheat oven to 350°F (175°C). Line a baking tray or pan with parchment paper.
Melt Chocolate & Butter – In a microwave-safe bowl, melt the dark chocolate and butter in 20-second intervals, stirring in between. Let cool slightly.
Mix Wet Ingredients – In a large bowl, whisk together eggs, caster sugar, and demerara sugar until pale. Stir in vanilla extract and melted chocolate mixture.
Combine Dry Ingredients – In a separate bowl, whisk together flour, cocoa powder, baking powder, and salt. Gradually fold into the wet ingredients.
Add Chocolate Chips – Gently fold in chocolate chips for an extra chocolatey bite.
Bake – Pour the batter into the prepared pan. Bake for 20–25 minutes, until the edges are set but the center remains slightly soft.
Cool & Serve – Let cool for 10 minutes before slicing. Enjoy warm for a gooey treat or let them firm up for a chewy bite!