Chicken pan pie

Ingredients

• 1 tablespoon vegetable or olive oil
• 500 gram chicken thigh fillets, cut into 2 cm pieces
• 1 medium brown onion, finely chopped
• 1 small carrot, finely chopped
• 2 sticks celery, finely chopped
• 300 gram button mushrooms, quartered
• 1 clove garlic, crushed
• 1 cup cream
• 2 tablespoon worcestershire sauce
• 2 teaspoon finely chopped thyme
• 1 sheet frozen puff pastry, thawed
• 1 egg, lightly beaten
• 2 tablespoon shredded parmesan
• 1 teaspoon poppy seeds
• mashed potato, to serve