Preheat the oven to 200ºC, fan 180ºC, gas 6. Bring a medium pan of water to the boil, add the broccoli and cook for 3 minutes. Drain and set aside.
Line a baking tray with baking parchment. Unroll the pastry and cut out 4 x 10cm rounds (use a small saucer as a template) and put on the tray. Cut out small leaves from the pastry trimmings to decorate the top of the pies. Brush with the milk and bake for 10 minutes, until risen and golden.
Meanwhile, heat the oil in a frying pan, then add the chicken and cook, stirring, for 5 minutes. Add the mushrooms and cook for a further 3 minutes, until the mushrooms are softened and the chicken is cooked through with no pink remaining. Pour in the soup and cooked broccoli, bring to the boil, then reduce the heat and let simmer for 2 minutes.
Meanwhile, pierce the bag of fine green beans with a fork and microwave on high for 3 minutes.
To assemble your pies, cut the cooked puff pastry rounds in half horizontally. Divide the bases between 4 plates, spoon the chicken mixture over each one then top with the lids. Serve with the cooked green beans on the side.
Chef's tip: steam the beans for a few minutes instead of using a microwave oven if you don't have one.