In a large mixing bowl, combine the shredded chicken, petits pois, crème fraîche and parsley and season with a little freshly ground black pepper.
Preheat the oven to 200°C, fan 180°C, gas 6. On a lightly floured surface, roll out the pastry to a thickness of a pound coin and stamp out 6 x 12cm rounds using a cookie cutter, or a glass with a thin rim. Spoon the mixture into the middle of each pastry circle, leaving a 1cm border. Brush the pastry border with a little of the milk then bring the edges together. Use your fingers to pinch and crimp them together to seal then brush all over with the remaining milk.
Transfer to a baking tray and bake in the oven for 25-30 minutes until piping hot throughout and golden.