Step 1

Preheat oven to 200C/180C fan-forced.

Step 2

Heat oil in a 6cm-deep, 22cm (base) and 25cm (top) heavy-based, ovenproof frying pan. Add chicken. Cook for 5 minutes or until just browned. Add leek, celery and carrot. Cook, stirring occasionally, for 5 minutes or until leek is tender. Add garlic, rosemary, thyme and sage. Cook for 1 minute or until fragrant. Add our. Stir to coat. Gradually stir in stock and milk. Bring to the boil, stirring occasionally. Remove from heat. Stir in corn. Season with salt and pepper.

Step 3

Stack pastry sheets on top of each other. Using a rolling pin, roll out to form a 27cm square. Place pastry on top of filling in pan. Fold in overhanging pastry to form a border. Brush with egg. Cut a cross in the centre of pastry to allow steam to escape. Sprinkle with sesame seeds.

Step 4

Bake pie for 30 minutes or until pastry is golden and puffed. Stand in pan for 5 minutes. Serve.