1. Preheat the oven to 170C(fan oven 150C), gas mark 3. Line a 20 cm (8 inch) square shallow cake tin with silicone paper or baking parchment.
2. Break up the chocolate into a heatproof bowl and add the butter. Set over a pan of gently simmering water and melt, stirring from time to time.
3. Meanwhile, prepare the caramel ripple mixture. Combine the soft cheese, muscovado sugar, vanilla extract and egg in a bowl and mix well until evenly blended. Set aside.
4. Stir the eggs and sugar into the chocolate mixture, then sift over the flour and gently fold in.
5. Spoon half of the chocolate mixture into the prepared tin, then alternately dollop teaspoonfuls of the caramel mixture and the remaining chocolate mixture on top. Using a xhopstick or skewer, lightly ripple together to make a marbled top.
6. Bake for 25-30 minutes until just set. Leave to cool in the tin for 5-10 minutes before cutting into squares. Transfer the brownies to a wire rack to cool completely.
Tips: These rich, rippled brownies are fantastic served with coffee. As they are quite dense, cut them into small squares and wrap in foil for lunchboxes.