Method

1. Preheat the oven to 190ºC / gas 5. Heat the butter and oil in a large, heavy-bottomed frying pan over a medium heat. Add the chicken pieces and fry, stirring, for about 5 minutes, or until browned. Add the bacon and garlic to the pan and continue cooking for a few minutes, stirring, until the bacon gives off its fat and becomes crisp. Tip in the celery and leek, and stir for a further few minutes until the vegetables soften.

2. Reduce the heat to medium-low. Sprinkle in the flour and cook, stirring around for 2 minutes to cook out the raw taste. Gradually stir in the milk and chicken stock to make a smooth sauce. Add the mushrooms and parsley. Transfer the contents of the pan to a large baking dish and smooth the surface.

3. Make the topping by mixing the breadcrumbs and grated cheese together. Sprinkle this generously over the top. Put the dish on a baking sheet and bake for 15–20 minutes until the topping is crisp. Serve piping hot.