Boil muscovado sugar, cream, and glucose together in a saucepan.
Caramelize caster sugar in a separate pan over low heat until golden-brown.
Pour the cream mixture over the caramel and simmer until the temperature reaches 102°C.
Stir in lemon juice, salt, and black pepper, then let cool.
Freeze the caramel in small moulds for at least 2 hours until set.
Grease the 5cm ring moulds with softened butter.
Dust the moulds with a mix of cocoa powder and caster sugar.
Melt the chocolate and butter over a bain-marie.
Whisk eggs and egg yolk until pale and fluffy.
Sift and whisk in icing sugar and arrowroot until the mixture reaches the ribbon stage.
Whisk the melted chocolate into the egg mixture.
Fill the ring moulds three-quarters full with the chocolate batter.
Press a frozen caramel piece into each mould, cover with batter, and chill for 30 minutes.
Preheat the oven to 200°C.
Bake for 5 minutes until a crust forms, then allow to cool.
Remove the moulds and chill the fondants for another 30 minutes.
Simmer milk, whisk in chocolate for the sauce, and set aside.
Preheat the oven to 180°C.
Bake the chilled fondants for 8 minutes until they rise.
Serve the fondants on chocolate sauce with nuts and pistachio ice cream.