To make the panna cotta; heat the cream, sugar and vanilla bean in a pot until almost boiling. Soak the gelatine leaves in cold water for a couple of minutes then squeeze out the water and stir into the hot cream.
Allow to cool slightly before adding the buttermilk, stir to combine and pour into individual moulds.
Allow to cool completely before placing in the fridge to set.
To make the syrup; bring honey and water to the boil and remove from the heat.
When cool, add the pistachios and the grapes.
To serve, turn out the panna cottas and spoon over the syrup.