Prepare the base: In a microwave-safe bowl or using a double boiler, melt 130g butter, 50g chopped dark chocolate, and 25g cocoa powder. Stir until smooth. Let this mixture sit at room temperature for 10 minutes to cool slightly.
Mix wet ingredients: Add 100g brown sugar, 50g white sugar, 1 tsp vanilla essence, and 3 room-temperature eggs. Whisk until smooth and glossy.
Add dry ingredients: Sift in 75g all-purpose flour, then fold gently with a spatula. Stir in 50g roughly chopped dark chocolate and 100g chopped walnuts.
Bake: Pour into a parchment-lined 8x8-inch pan, leaving some overhang for easy removal. Bake in a preheated oven at 180°C/350°F for 22–25 minutes until the top looks set but slightly soft in the center.
Caramel topping: While still warm, drizzle caramel sauce over the brownies. Sprinkle more chopped walnuts and some chocolate chips on top.
Cool & garnish: Let brownies cool completely in the pan. Use the parchment overhang to lift them out. Drizzle more melted chocolate and caramel on top. Slice into squares and serve.
