Blend the sauce mix with 300ml cold water in a saucepan. Bring to the boil, stirring, and cook gently for 3 minutes until thickened. Remove pan from the heat, add the crème fraîche, lemon juice and chives and season to taste. Set aside to cool for 1 hour.
Melt 15g of the butter in a frying pan and gently cook the chicken breasts for 7–8 minutes on each side, over a medium heat, until cooked through. Remove chicken from the pan, chop into small pieces and stir into the mushroom sauce, along with any pan juices. Preheat the oven to 200°C (gas 6).
Melt the remaining butter and mix with the oil. Take half a sheet of filo (measuring about 24cm square) and brush with a little of the oil mixture, then place three more pieces of the filo on top, at angles to each other, to form a star shape, lightly oiling each sheet.
Place a quarter of the chicken mixture in the centre, then gather up the pastry edges, pinching tightly to form a parcel. Repeat to make three more parcels.
Place the parcels on a non-stick or lightly greased baking sheet and bake for 15–20 minutes until the pastry is crisp and golden. Serve immediately, garnished with salad leaves.
*For an attractive finish, tie the cooked parcels with fresh chive stalks or sprigs of parsley with long stems. *Filo pastry varies in thickness, size and weight. If using a thicker filo, six sheets will be enough. Each half sheet should measure about 24cm square. *Packets of sauce mix are readily available from supermarkets and makea convenient standby to keep in the cupboard. Alternatively, make a home-made sauce. You will need 300ml.