Make the sauce. Melt the butter in a small saucepan over a medium heat, add the sugar and syrup and cook gently until the sugar dissolves. Stir in the cream and vanilla essence and bring slowly to boiling point. Remove from the heat and leave to stand while cooking the foil parcels.
Lay 4 pieces of foil on the work surface and arrange a pile of the fruit in the middle of each one. Seal the parcels, then cook on a low heat on the barbecue for 8–10 minutes. Carefully open the parcels and serve the fruit topped with the caramel sauce.