Chicken and Mushroom Pie

500g cooked chicken (roast or fried) 1 x 425g can mushrooms, sliced 50g butter + 1 to 2 tbsp cooking oil 3/4 cup flour, sieved 500ml hot milk 1 whole big onion, 6 cloves (stick the cloves into the onion) 1 stick celery, diced 1 tsp chopped parsley 1-2 dried bay leaf (optional) salt, pepper ready rolled puff pastry - thaw for a few hours first beaten egg for glazing 1. Preheat oven to 180'C.
2. Melt butter in pan. Add cooking oil. 3. Add sifted flour to pan, mix well until flour turns slightly golden.
4. Remove pan from heat, and slowly stir in hot milk to avoid lumps. 5. Add clove-studded onion, chopped celery and bay leaf to sauce.
6. Return pan to stove and simmer gently ~ 20 mins.
7. Add cooked chicken chunks, sliced mushrooms and chopped parsley.
8. Simmer another 10 minutes.9. Cool completely. (Sauce will thicken upon cooling)
10. Thaw puff pastry to room temperature.
11. Unroll pastry and cut several pieces of equal length (eg 20cm each)
12. Place filling on one piece of pastry, making sure to leave ~2-3 cm border all round.13. Place another sheet on top of filling. Seal edges all round by pressing with fingers or fork.
14. Take skewer and prick the pastry sheet all over (to allow heat to escape).
15. Glaze with beaten egg. Continue with the rest of the pastry.
16. Bake 180'C, 30-40 minutes. "NOTE: If white sauce is too thick, add water accordingly. Sauce should be thick but not runny."