In a heavy based pot brown diced beef and onion with a splash of oil.
Sprinkle with 2 tablespoons of flour. Continue to cook for a minute before adding beef stock. Cook covered over low heat for 40 minutes.
In a separate saucepan fry mushrooms in butter moving around for 3 minutes then add to beef stew and continue cooking for another 10 minutes.
The mixture should be thick at this point - if not stir in 1 teaspoon of corn flour as directed by packet. Fill pots with beef mix, top with pastry, brush with egg wash and bake in oven until the pastry is golden brown.
TIP: Whisking an egg with a dash of water and brushing the egg wash over the pastry will give it a golden crust.