Rinse the raspberries. Mix the raspberries, sugar, vanilla sugar, lemon juice and cream in a saucepan. Let simmer for 10-15 minutes until syrupy. Puree and pass through a sieve. Stir in the orange zest and keep warm.
Melt the chocolate over a hot, not boiling, water bath. Leave to cool slightly. Add the raspberry puree. Pour the mixture into chocolate molds and let harden. Serve with sugared raspberries, if desired.