On a separate chopping board (ideally red), cut the steak into cubes. Season with black pepper.
Chop the pancetta. Remember to thoroughly wash your hands after handling raw meat.
Heat the oil in a casserole dish, add the steak and brown.
Remove the steak from the pan and place on a plate.
Add the pancetta to the casserole dish and fry until golden. Remove the pancetta from the pan and place on the plate with the steak.
Reduce the heat and add the onions, carrots, celery, mushrooms and garlic to the casserole dish. Mix and cook for 5 minutes.
Make up the beef stock with boiling water.
Add the chopped tomatoes, tomato puree, beef stock and bay leaves to the casserole dish. Mix well.
Add the beef and pancetta to the casserole dish and mix well.
Place the lid on the casserole dish and bring to the boil.
Place the casserole dish in the oven and cook for 90 minutes.
While the casserole is cooking, bring a saucepan of water to the boil and add the potatoes.
Reduce the heat and simmer for 10-15 minutes until the potatoes are tender.
Drain the potatoes and leave to cool.
Remove the casserole dish from the oven and remove the lid.
Carefully arrange the potatoes on top of the casserole.
Grate the parmesan cheese and sprinkle on top of the potatoes.
Cook in the oven for a further 10 minutes without the lid until the potatoes are golden.