Unroll the pastry and cut out 4 circles a little larger than the top of a 300ml pie dish. Place on a baking tray and chill in the fridge for at least 30 minutes.
Preheat the oven to 200°C, fan 180°C, gas 6. Meanwhile, heat the oil in a large saucepan over a medium heat and gently fry the onion and garlic for 3-4 minutes until softened. Add the mushrooms and rosemary and cook for a further 5 minutes until softened.
Pour in the mushroom soup, then stir in the turkey. Season with freshly ground black pepper. Divide the mixture among four 300ml pie dishes. Wet the rim of each pie dish with water, cover each with a circle of pastry and press the pastry over the sides to seal.
Brush the pie tops with milk and bake in the oven for 20-25 minutes, until risen and golden.
Cook’s tip: you can add more depth of flavour to the mushroom and turkey mix by adding a dash of wine when you add the mushroom soup.