Preheat the oven to 180°C, fan 160°C, gas 4. Heat 2 tablespoons of the oil in a large pan and cook the leeks for 10 minutes until softened. Sprinkle in the flour, then slowly stir in the milk. Bring to a simmer to thicken, then add the turkey and ham to the mixture.
Stir in the parsley and mustard and cook for a further 2 minutes. Pour into a 1.5-litre baking dish.
Lightly scrunch the 4 filo sheets and place on top of the pie, then scatter over the cranberries and orange zest. Brush the filo with the remaining oil and bake for 25 minutes until golden. Serve with your choice of green vegetables.