1. Preheat the oven to 200°C/400°F/Gas 6.
2. Add the mince and onion to a frying pan and dry fry until the mince is lovely and brown and cooked through.
3. Add in the Worcestershire sauce, ketchup, flour and season with lots of lovely black pepper. Stir it all through and cook for a further minute.
4. Add the potatoes to the pan with 350ml of water and cook for a further 15 minutes.
5. Spoon everything into your pie dish.
6. Unroll the pastry sheet and cut a 1-inch pastry strip to go round the edge of your pie dish.
7. Dampen the edge of the dish with a little water and fit the pasty strip so it goes all the way round, pressing down firmly to secure.
8. Brush the strip with a little bit of egg wash, then top with a pastry sheet, pressing the edges together.
9. Trim your pastry to fit the dish, pierce 2 steam holes in the top and brush with the rest of the beaten egg.
10. Cook for 25 minutes until it's lovely and golden brown.
Recipe courtesy of The co-operative food