Prepare the greaseproof paper. Cut 4 long strips of greaseproof paper about 5mm wide. Cut each strip in half and position two in each dariole mould so that they cross in the base of the dariole mould and come up the sides and beyond the lip of the dariole mould. This will help remove the pies if necessary.
Make the hot water crust pastry. Place the two flours, salt and butter into a large bowl. Dice the butter. Rub the butter into the flour between your thumb and finger tips until it resembles fine breadcrumbs. Place the boiled water into a pan. Add the cubed Trex / baking block. Set over a low heat on the hob to allow the fat to melt. Make a well in the breadcrumb mixture and pour the melted fat and water mixture in. Use a knife to cut through the mixture (it’s hot) to create a dough. Once the mixture starts coming together use your hand to knead the dough for a minute or so until smooth.
Divide the pastry. Divide the pastry into 5 roughly equal pieces (1 will be for the lids). Place one piece onto a lightly floured work surface and cover the other 4 with clingfilm to keep them warm.
Line the dariole moulds. Partially roll out the piece of hot water crust pastry until you have a thick disc (either with a rolling pin or simply by flattening it to a disc with your hand). Ease it into the mould. Use your thumbs to ease the pastry up the sides of the mould, turning the dariole mould as you do so. Bring the pastry up the side of the dariole mould until it is slightly above the lip of the container. Aim to ensure the pastry is roughly the same thickness all over. Patch the pastry if it breaks. Place into the fridge to chill. Repeat with the remaining 3 dariole moulds.
Shape the pastry lids. Roll out the final piece of pastry on a lightly floured work surface. Use a plain cookie cutter to cut 4 discs from the pastry. Place the ‘lids’ onto a baking tray or large plate. Place in the fridge to chill.
Start to make the filling. Place a little oil into a large pan or wok, set it over a gentle flame. Add the chopped onions. Allow it to cook, without colouring, for about 5 minutes until translucent. Stir frequently.
Make the ‘gravy’. Crumble the oxo into a heat proof jug. Add the vegetable gravy granules. Pour in 1/2 ltr (1 pint) of boiling water. Stir to mix.
Add the quorn. Add the quorn mince to the onions. Mix briefly. Pour over the ‘gravy’. Stir. Allow the quorn mixture to cook down slowly on a low to medium heat.
Meanwhile, prepare the potatoes. Place the peeled & cubed potatoes into a pan. Cover with water and place on the hob over a medium heat. Allow the water to come to the boil, turn the heat down and cook gently until the potatoes are almost cooked but still with a slight resistance. Strain the potatoes and add to the quorn mixture. Stir to combine. Add the HP sauce and mix again. Taste and season with a pinch of salt as required.
Thicken the gravy, (optional). By this point the quorn gravy will have reduced and will have thickened slightly. To make it a little thicker place the cornflour into a cup. Add a small amount of water. Stir to make a smooth paste. Add to the quorn mixture whilst stirring. The mixture will thicken fairly quickly. If it feels a little too thick for your preference add water (a little at a time) until it is how you like it.
Cool. Pour the quorn & potato mixture into a wide bowl (such as a pasta bowl) and set aside to cool completely.
Pre-heat the oven to 200c / Fan 190c / Gas 6. Place a baking tray, large enough to hold the 4 pies, into the centre of the oven.
Fill the pastry cases. Remove the chilled pastry moulds from the fridge. Carefully fill the pies with the cold filling aiming not to leave any large air pockets. Avoid over filling the pies.
Affix the lids. Use a sharp knife to cut a small hole in the top of the lids to act as a steam hole. Place the lids on top of the pies and carefully seal them by crimping the pastry with your thumb and two forefingers.
Glaze the pastry lids. Using a pastry brush, paint the pastry lids with some of the beaten egg. Try not to get any egg on to the moulds, as this may ‘glue’ the pies to the mould & prevent them from turning out successfully.
Place the dariole moulds on to the hot baking tray. Place into the centre of the oven and bake for about 40 minutes. Rotate the tray after 30 minutes.
Remove from the oven. Once the pies are cooked through and the pastry is golden brown remove them from the oven. Place on a cooling tray. Allow to cool for a couple of minutes. Tip the moulds to remove the pies, use the greaseproof paper ‘handles’ if needed. Enjoy served with vegetables of your choice.