Low-fat fish pie

Ingredients
* 40g butter, melted
* 1 leek, trimmed, washed, thinly sliced
* 2 tablespoons plain flour
* 350ml fish stock
* 2 tablespoons lemon juice
* 1kg thick white boneless fish, cut into 3cm pieces
* 9 sheets filo pastry
* olive oil cooking spray

Method
1. Preheat oven to 200°C. Grease a 5-cup capacity ovenproof dish. Cook butter and leek in a frying pan over medium heat for 3 minutes or until tender.
2. Sprinkle flour over leek mixture. Cook, stirring, for 2 minutes. Remove from heat. Add stock and lemon juice. Stir well. Return to heat. Cook, stirring, over medium heat for 6 minutes or until thick.
3. Remove from heat. Add fish, and salt and pepper. Cool completely. Place 1 sheet of filo onto a flat surface. Spray with oil. Fold in half. Place into pie dish. Repeat with 5 more sheets of filo, placing into dish so base and sides are covered.
4. Spoon fish mixture over filo. Cut remaining 3 sheets of filo into quarters. Scrunch each quarter into a ball. Place onto fish mixture. Spray with oil. Bake for 30 minutes or until pastry is crisp. Serve.