Heat 1 tablespoon of the oil in a large pan and cook the onions for 5 minutes until they are beginning to soften. Add the mushrooms and cook for a further 5 minutes.
Add the remaining tablespoon of the oil to the pan, and fry the beef and bacon pieces until browned on all sides.
Stir the flour into the pan, cook for 1 minute, then gradually stir in the stock and bring to the boil.
Turn down the heat to low, then place a lid on the pan and simmer for 1 hour - 1 hour 30 minutes, stirring occasionally to avoid sticking. When the meat is tender, spoon into a 20-23cm pie dish and cool.
Preheat the oven to 200°C, fan 180°C, gas mark 6.
Unroll the pastry and cut two narrow strips from the short end of the sheet. Place the strips around the edge of the pie dish and brush with water.
Place the remaining pastry sheet over the pie dish, pressing the edges down well to seal. Trim off the excess pastry, you can use the trimmings to make decorations for the top.
Cut a small hole in the centre of the pie with a sharp knife to allow the steam to escape. Brush the top of the pie with a little milk.
Place the pie dish on a baking sheet in the oven and cook for 20-25 minutes until golden.
*All information included in this recipe has been provided by BakeAway.