Soak the gelatine sheets in a small bowl of cold water for 5 mins.
Mix together the cream, milk and sugar in a medium saucepan and heat gently until the sugar dissolves.
Lift the gelatine from the water, squeeze out any excess liquid and put into the pan with the cream mixture. Heat very gently for 1-2 mins until the gelatine has dissolved.
Put 50g (2oz) of the chopped chocolate into a heatproof jug and pour over half of the warm cream. Stir gently to melt the chocolate.
Split the vanilla pod lengthways and scrape the seeds into the remaining cream in the saucepan.
Rinse 6 x 150ml (1/4 pint) glasses with cold water and do not dry. Divide the chocolate mixture between each glass. Sit the glasses on a tray with some coins or a piece of scrunched up foil under one side to slant the mixture as it sets. Chill for 1hr. Keep the vanilla custard over a pan of warm water to prevent it from setting.
When the chocolate mixture has set, return the glasses to upright and slowly pour on the vanilla custard. Return to the fridge for 1 hour to set.
Warm the cherry conserve with the fruit juice in a small saucepan. Bring to the boil and simmer for 2-3 minutes. Remove from the heat and stir in the remaining chocolate. Stir until the chocolate has completely melted. Leave to cool.
Serve the panna cotta chilled with some of the cherry chocolate sauce spooned on top.
The panna cotta and the sauce can be made up to 3 days ahead of time. Keep covered in the fridge.
The black cherry and chocolate sauce can also be served warm. Hand round a bowl of the sauce to spoon on top.
Don’t throw away the vanilla pod once the seeds have been removed. Use it to make some vanilla sugar!
