Melt the chocolate in a heatproof bowl suspended over a saucepan of gently simmering water. Make sure the base of the bowl doesn’t touch the water to prevent the chocolate burning. Once melted, add the cream, milk and cardamom.
Meanwhile, soak the gelatine leaves in cold water for five minutes, until soft and pliable. Squeeze out the excess water and add to the chocolate mixture. Stir until the gelatine has dissolved.
Add the sugar and gelatine to the chocolate mixture and mix until the sugar dissolves. Strain the chocolate through a fine sieve and pour into six moulds, each about 150ml in capacity. Allow to cool, then refrigerate for at least four hours, until set.
To make the rose syrup, add the sugar and water to a pan and bring to the boil. Add the rose water and raspberries and reduce heat and allow to simmer until reduced. Sieve the mixture and allow to cool.
Turn out the panna cottas: this is easier if you first dip the moulds into very hot water. Place one pannacotta on to a plate. Drizzle over the rose syrup and decorate with the strawberries, raspberries, blackberries, blueberries and pistachios.