1. To begin, preheat your smoker or oven to 350F and line a baking sheet or foil tray with baking paper.
2. In a large saucepan over medium heat, melt the butter. Add the flour and cook, stirring constantly, for 1 minute or until mixture bubbles. Add chicken stock, then cook for a further 2-3 minutes, whisking to remove any lumps.
3. Add the thickened cream and cook for a further minute or until the mixture boils and thickens. Season to taste.
4. In a cast iron skillet, cook leeks until semi transparent and soft. Add the turkey, ham, chopped mushrooms, parsley, chives and green onion. remove from the cast iron and fold into the cream sauce mixture until well incorporated. Remove from the heat and allow to cool completely.
5. While the mixture cools, roll out the pastry on a lightly floured surface to form a 12 x 12 inch rectangle. Cut in half lengthways to give two 6 inch-wide pieces. Place one pastry sheet on the lined baking tray and spread with the cooled turkey mixture, leaving a 1/2 inch border.
6. Fold remaining sheet of pastry in half lengthways and use a sharp knife to make cuts in the folded side, about 1/4 inch apart and leaving a 1/2 inch border on the unfolded side.
7. Carefully open the pastry back out and place over the filling, pressing the edges to seal. Trim the edges if necessary, then brush all over with the beaten egg.
8. Bake the pie for 25-30 minutes until puffed and golden. Slice the pie and serve with cranberry sauce.