Add the fat or dripping to a casserole dish and fry the the onion, carrots and garlic in the dripping or goose fat; when soft transfer to a plate.
Cube the ox cheeks into bite-sized pieces and seal a few at a time, transferring to the plate once browned.
Whilst the last batch of beef is frying add a little extra fat to the frying pan – we used goose fat – and add a tablespoon of plain flour and cook for a few minutes before adding back the onion, carrot, garlic and the rest of the meat.
Add the wine, top up with water until the top of the meat is just covered and add beef stock cube.
Season with salt and pepper, cook in a medium oven (170C / GM3) with the lid on for 2 hours.
If the filling needs thickening, put a teaspoon or two of cornflour into a small bowl, then add a few spoons of the gravy, mix well and return to the casserole. (Never thicken by adding cornflour directly to the casserole as you will never get the lumps out.) Check the seasoning and add more salt and pepper if needed.
Transfer the filling to a pie dish, place a pie bird in the middle, wet the edges of the dish, then cover with a sheet of puff pastry with a hole cut for the bird. If you do not have a pie bird use an upturned egg cup, and make a few small holes in the pastry to allow the steam to escape.
Decorate the top of the pie with the leftover scrapes of pastry, and brush with a beaten egg. Return to the oven and bake at 220C / GM7 for about 40 minutes until the pastry has risen and is golden brown.