Prepare the rillette of duck confit: Shred the duck confit into a large bowl using your fingertips. Melt the duck fat and mix through the shredded duck confit. Add the sliced chives, flat leaf parsley, gherkins, cocktail onions and the horseradish to taste and fold through the duck meat taking care not to overwork the mixture. Add the sauce Perigeux and cognac and season to taste with salt and freshly ground pepper.
Line a tray with silicon paper and place 8 ring moulds, 7cm wide by 1_cm deep, onto the paper and divide the rillette mix between them so that the moulds are three quarters full. Using a palette knife evenly spread the rillette so that the surfaces are flat. Refrigerate for 15 minutes to allow the fat to set. Once the rillettes are firm, spoon the diced foie gras and julienne of truffle over the top. Pour the Armangac jelly into a jug and fill the moulds to the top. Return to the fridge to set.
Check the level of the jelly after 15 minutes. If the rillette is not packed tightly into the moulds, this may allow for some of the jelly to seep through and they may need to be topped up with more jelly. Allow the rillette to stand in the fridge until the jelly is set before unmoulding. Pour the left-over jelly into a small, ½cm deep, cling-film lined tray and refrigerate to set. When set, turn out the jelly onto a clean chopping board and cut into ½cm cubes. Refrigerate until ready to use.
To garnish: Place the sliced shallots, artichokes, duck gizzard confit, chopped walnuts and 25ml blackberry and walnut vinaigrette into a bowl and mix together. Lightly season with salt and freshly ground pepper. Run the tip of a sharp, thin knife around the inside of the rillette moulds and gently lift off the moulds taking care not to break the jelly. Place a rillette in the centre of a plate and surround with the dressed shallots, artichoke, gizzard and walnuts. Spoon the cubed Armangac jelly around the garnish. Dress the mesculn leaves with the remaining blackberry and walnut dressing, lightly season with salt and freshly ground pepper and arrange around the rillette. Garnish with the chive tips and tarragon leaves.