Soak the gelatine in cold water for approx. 5 mins.
Cut open the vanilla pod lengthwise, scrape out the seeds, combine with the cream, milk and sugar and bring to the boil, reduce the heat, boil down to approx. 400 ml, remove the pan from the heat. Break the chocolate into pieces, add to the hot mixture, stirring as the chocolate melts. Drain the gelatine, stir into the hot mixture, then pour the mixture through a sieve into a measuring jug. Rinse 4 ramekins (each with approx. 150 ml capacity) in cold water. Pour the mixture into the ramekins. Cool completely, cover and leave to set in the fridge for approx. 4 hrs.
Halve the melon and remove seeds. Cut half of the melon flesh into slices and/or scoop out half of it into balls. Cut the remaining melon flesh into pieces, combine with the lemon juice and honey, then puree until smooth.
To serve: Carefully slide the tip of a knife around the edges of the panna cotta. Briefly dip the ramekins in hot water. Turn out the panna cotta onto plates. Decorate with the melon puree and melon segments. Shave off pieces of the chocolate and use to decorate the panna cotta.