Heat a knob of butter in the frying pan, and fry the walnut halves for 1-2 minutes until they are just toasted. Allow to cool and then blend in a food processor until finely chopped.
Roughly mash the Stilton and butter together in a bowl. Mash in the port and peppercorns, then chill in the fridge for at least three hours but preferably overnight.
Mix the parsley into the chopped nuts and place into a small bowl.
Roll teaspoonfuls of the mixture into small balls, then dip them into chopped nuts until evenly coated. Place onto a tray lined with baking paper and chill in the fridge until ready to serve.
To serve, pop a cocktail stick into each one and pile onto a plate.