Step 1

Heat the oven to 200C/fan 180C/gas Spread the mince and chestnut mushrooms out on a non-stick baking tray. Cook for 20-25 minutes, stirring now and again until the mince is browned and the mushrooms have taken on some colour and their excess liquid has evaporated.

Step 2

Meanwhile, put the dried mushrooms in a bowl and pour over 150ml of the hot stock.

Step 3

Heat the olive oil in a shallow casserole or deep ovenproof frying pan and cook the onion until softened. Add the garlic, cook for a minute then add the rice and stir through the oil and onions until fully coated.

Step 4

Strain the mushroom liquor (leaving behind any grit). Chop the soaked mushrooms and stir them in, then gradually add the mushroom liquor, stirring as you go. Add the rest of the beef stock a ladleful at a time, adding more once the previous ladleful has been absorbed, until the rice is nearly cooked. Stir in the passata then tip in the roasted minced beef, mushrooms, tomato purée and Worcestershire sauce, celery salt and oregano. Bring to a simmer, adding a little more water if it looks dry. Stir in ¾ of the mozzarella. Sprinkle the rest over the top with the parmesan. Put in the oven for 25 minutes, uncovered, until golden and bubbling.