Melt the butter with the olive oil in a saucepan, add the chopped onion, leek, garlic, mushroom and thyme, season with salt and pepper and cook over medium – high heat for 2 -3 minutes until lightly coloured. add in the flour and cook for a minute to coat the vegetables. Pour the white wine, cream and stock and bring to the boil. Add the turkey pieces and reduce to medium/ low heat and leave to simmer gently for several minutes until it starts to thicken. Remove from the heat and check the seasoning.
Pour into 2 oven dishes.
Cover with the leftover mash potato, and cover with parchment paper and cling film.
Place the first pie in the oven and bake for 20 minutes. Serve while piping hot.