Chicken and mushroom pie

Name: Chicken and mushroom pie
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Cuisine: European, British
Ingredients: 1 tbsp vegetable oil; 2 onions, finely chopped; 380g mushrooms, sliced; 600g skinless chicken thigh fillets, cut into 1cm strips; 2 garlic cloves, crushed; 2 tbsp plain flour; 1 reduced-salt chicken stock cube, made up to 300ml; 100g soft cheese; 15g fresh flat-leaf parsley, finely chopped; 375g pack ready-rolled lighter puff pastry; 1 egg, beaten; 500g fresh greens, stalks removed, leaves shredded