Preheat oven to Gas Mark 5, 190ºC, 375ºF.
Take 4 pieces of foil. Lay onto the foil the potato slices and leeks, place the chicken on top. Spoon 2tbsp wine and 3tbsp cream into each parcel, add basil and tarragon and season to taste.
Scrunch the foil and seal the parcel. Place in a hot oven for 20-25 minutes until all ingredients are tender.
Turn onto a plate and serve with a green salad.