Preheat oven to 200°C.
Heat oil in pan over medium heat. Brown chicken, add mushrooms, cook 2 minutes.
Add combined evaporated milk, cornflour, mustard and stock powder. Bring to boil, simmer covered 6 minutes.
Remove from heat, stir in asparagus. Spoon mixture into 4 individual ovenproof dishes.
Divide pastry into 4, top dishes with pastry. If desired, brush pastry with a little egg yolk and slit pastry. Bake 15-20 minutes until golden. Serve.