Saute the chicken breasts in a pan with the olive oil until golden on all sides and just cooked through.. Remove and sen set aside.
In the same pan heat the butter and sauté the leeks until they soften, about 5 minutes. Add the garlic, parsley and mushrooms and cook for a further 4 – 5 minutes until they are cooked.
Cut the chicken up into small to medium pieces and return these to the pan with the vegetables, heat through.
Stir through the flour until it is well distributed and cook for a minute. Add the stock and allow the sauce to thicken, about 3 – 4 minutes. Ensure that all the flour has cooked through.
Add the creme fraiche and parmesan and cook for a further couple of minutes. You will now have a very creamy sauce. Check the seasoning and add salt and pepper to taste. All this mixture to cool slightly.
Preheat your oven to 180 C / 350 F
make your béchamel sauce by melting the butter and then adding the flour to form a roux. Add the milk bit by bit, whisking all the time until you have a nice smooth sauce. Add the Dijon, salt and pepper and cheese.
Divide the mixture amongst the 6 pancakes and roll each up and place in an appropriately sized oven dish. Ensure that they are quite tightly packed next to each other.
Cover the filled pancakes with the béchamel sauce and bake for 25 – 30 minutes until