Make six foil parcels and divide the plums between them.
Combine the muscat with the honey, sprinkle the plums with this mixture, add some butter and lemon thyme. Seal the parcels tightly, cook over gentle heat for 15 minutes.
Whip the cream to soft peaks, add the sugar. Open the parcels, discard the lemon thyme, add a generous tablespoon of chantilly cream. Serve immediately.</