Instructions

1. Put the potatoes into thick slices, put them into a large pot of salted water and bring to the boil. Cook for 8-10 minutes, until the potatoes are tender but not fully cooked through. Strain into a colander and allow to cool.
2. Meanwhile, heat the butter (and a little bit of oil to stop the butter from burning) in a large, shallow saucepan. Add the chicken and smoked bacon and cook for 4-5 minutes, then add the leeks, garlic and mushrooms, together with a little seasoning. After a further five minutes, sprinkle in the flour and use this to dry up any liquids in the pot and to thicken the sauce. Pour in the white wine, grated cheese and milk and allow the mixture to come to a gentle boil, stirring all the time. Add the cream as well now also . Season lightly and add the wholegrain mustard. Simmer for 5-6 minutes and then transfer to a large casserole dish.
3. Neatly arrange the sliced potatoes on the top, Sprinkle with some salt, pepper, cheese and breadcrumbs and bake in a preheated oven (190C/375F/Gas Mark 5) for approximately half an hour.