1. Put the caster sugar, dextrose, skim milk powder, dark muscovado sugar and cocoa powder in a bowl and mix to combine.
2. Put the carob bean powder in a separate bowl. Add 2 tablespoons of the sugar mixture and mix together well.
3. Pour the milk, cream and water into a large heavy-based saucepan over a medium heat. Whisk in the carob bean powder mixture and continue to heat, whisking in the sugar mixture as you go, until it hits 85°C (185°F). Remove from the heat, add
the chocolate and whisk together until the chocolate has melted into the mixture and everything is well combined.
4. Pour into a suitable lidded container and leave to cool in the freezer for 1 hour, or until the mixture drops to 4° C (39°F).
5. Turn on your gelato maker so it begins the freezing process.
6. Pour the mixture into your gelato maker. Once the mixture reaches -4°C (25°F) or is the consistency of soft-serve ice cream (this should take about 30 45 minutes) detach the canister or scoop the gelato into a pre-cooled lidded container.
7. Transfer to the freezer and leave for at least 1 hour to harden before serving.