Preheat the oven to 200 C / Gas 6. Using a small knife, cut a cross into the top of each chestnut. Place on a baking tray.
Bake the chestnuts in the oven for 30 minutes until the outer shell pulls away at the cross and the inner nut is tender. Remove from the oven and peel, discarding the shells. Roughly chop the inner nut, toss in a little salt and set aside. Reserve 3 nuts, halved for the decoration.
For the salmon pate:
In a food processor, combine all of the ingredients for the salmon pate and blend until smooth. Using your hands, greased if necessary, form the pate into 6 cakes. Roll the sides of the cake in the chestnuts. Chill in the fridge for 1 hour.
Remove from the fridge and arrange on a serving plate and garnish with a half chestnut and some fresh chives.