• Begin by chopped the 150g dark chocolate finely and place in a medium heatproof bowl
• Roughly chop the pistachio nuts and set aside
• Line the baking tin with clingfilm
• Make the caramel by putting the caster sugar (in an even layer) in a heavy based saucepan and let cook over a moderate heat, swirling around the pan a couple of times to cook evenly. The sugar should first melt, then turn a lovely amber colour
• Once the sugar has dissolved and the colour is deep amber, carefully add the muscovado sugar, butter and cream. Take care as the mixture may bubble up. Don't worry if the caramel solidifies in places. Put the pan back on a gentle heat and cook for around 5 minutes more, stirring frequently until it is smooth. Do not let the caramel boil
• Stir in the vanilla, sea salt, pistachio nuts and raisins. Pour the mixture over the chopped chocolate. Stir quickly to combine, then allow to sit for 2 minutes whilst the chocolate melts. Stir again and keep on mixing until the caramel and chocolate is fully combined. Pour into the prepared baking tin, level the surface and allow to cool to room temperature. Once cool, cover with clingfilm and transfer to the fridge to set for 4 more hours (or overnight)

Covering in Dark Chocolate

• Remove the caramel from the tin and clingfilm. Chop into 25 pieces
• Chop the chocolate finely. Place ⅔ of it into a small heatproof bowl and melt in the microwave. I do this by heating in 30 second bursts on full power, stirring occasionally. Once the chocolate has almost melted I add the remaining ⅓ chocolate and stir until it is all completely melted
• Using a dipping fork (or household fork) dip chunks of caramel into the chocolate until fully coated. Tap gently to remove any excess chocolate and leave to set on greaseproof paper
• Keeps in the fridge for up to 1 week. Bring to room temperature before serving