FILLING

1. You can either cook the beef etc in a frying pan and transfer to an oven safe casserole dish or something similar, or if you have a cast iron dutch oven, you can cook off the ingredients on the stove, then transfer the whole thing to the oven
2. Preheat the oven to 350˚f / 180˚c. Place a large cast iron dutch oven (mine is a 5.5 quart), over high heat. Once heated, add a glug of olive oil, and add half of the beef. Cook until golden brown on all sides. Remove and set aside. Repeat with the second half of the beef, and set aside with the first half.
3. Reduce the heat to medium. Add another glug of oil to the pan, and add the onion, garlic, and a big pinch of salt. Cook for 5 minutes, stirring often, until the onions are translucent. Add the mushrooms and cook for a further 5 minutes.
4. If you are using a frying pan and transferring to a casserole dish, transfer now, then add the thyme, bacon, and stock. Season well with salt and pepper.
5. Cover the dish and transfer to the oven. Bake for 2 hours, stirring occasionally, until the meat is tender and the gravy is bubbling.
6. Carefully remove from the oven. In a small bowl, mix the water and corn starch until smooth. Stir into the pie filling. Return to the oven, and bake, uncovered, for 45-55 minutes, stirring every 10 minutes or so, until the gravy has thickened.
7. Remove from the oven and allow to cool to completely, or, if preparing ahead, store in the fridge until using. (It is ideal if the mixture is cold when assembling the pies, so if possible, give it some time in the fridge if you can)

ASSEMBLY AND BAKING

1. On a lightly floured surface, roll out one of the rectangles of dough to approximately ¼ inch (6mm) thickness. Line each pie dish, leaving a little dough overhanging. Re-roll scraps if needed to finish lining all of the dishes, or use a little of the second rectangle of dough.
2. Place the dishes on a baking sheet, and rest in the fridge for about 10 minutes to firm up the pastry.
3. Divide the filling between the lined dishes, fill each dish with enough filling to just reach the top of the dish (see photo for reference). You may have a little bit leftover.
4. Roll out the second rectangle of dough to ¼ inch thick. Cut a circle a little wider than the pie dish, and place over the filling. Trim the dough so it is flush with the edge of the pans, and seal the top crust to the bottom by crimping with a fork. Cut a vent in the top crust.
5. Repeat with the rest of the pies, re-rolling scraps of pastry if needed.
6. Rest the pies in the fridge for 20 minutes. While they are resting, preheat the oven to 350˚f / 180˚c. Brush the tops of the pies with eggwash. Bake for 30-40 minutes, until the pies are golden brown and the filling is bubbly. Remove from the oven and cool slightly before serving. Leftovers can be frozen.