In a medium saucepan melt the butter, stir in the flour and cook over a gentle heat for a few minutes.
Slowly add stock and milk a little at a time, stirring as you do so to stop lumps forming. Allow to gently simmer and thicken for 10 minutes taking care to scrape the bottom of the pan.
Boil the pasta in a large pan until cooked. Drain, reserving some of the water, and return to the pan.
Place the oil in a non stick frying pan and fry the onion on a medium heat for a few minutes until translucent. Add the mushrooms and cook until soft. Transfer the onions and mushrooms to a plate.
Add the turkey and ham to the pan and fry for 10 minutes until cooked.
Transfer to an oven proof gratin or lasagna dish, sprinkle with the breadcrumbs, and top with the chees.
Bake at GM4 / 180C / 350F for about 12 minutes until piping hot and the cheese has melted.
This recipe is 18 Weight Watchers Smart Points per portion