Preheat the oven to 190°C and grease a 32x23cm tin with parchment.
Melt the granulated sugar in a saucepan until dark brown then add salt and 60ml of cream.
Stir in the remaining cream and butter until the caramel is smooth and leave to cool.
Sift the flour, cocoa powder, and salt into a large bowl.
Melt the dark chocolate and butter in a pan and allow to cool slightly.
Whisk eggs, sugars, and vanilla until thick, then combine with chocolate and fold in flour.
Layer half the batter, the caramel, and remaining batter in the tin and bake for 25-30 minutes.
Drizzle melted white chocolate over the cooled brownies before cutting into 12 pieces.