If you want to make the cheese crust, heat the oven to 200C/180C fan/gas 6. Season the cheese with the cracked black pepper and scatter evenly over a baking tray lined with baking parchment. Bake for 8-10 mins or until golden, then set aside to cool. Break into shards. Will keep in an airtight container for up to two days.

Put the stock and parmesan or grana padano rinds in a saucepan, bring to a boil, then turn down to a simmer. Melt one third of the butter in a large, shallow saucepan, add the onion and fry gently over a low heat for 8-10 mins or until soft but still white. If the onions look dry at any point add a touch more butter to the pan.

Stir the rice into the onions, turn the heat up slightly and cook for 3 mins, stirring until the rice is coated in butter and turns a pearly translucent white. Pour in the wine and stir for about 2 mins until the alcohol has evaporated.

Add a ladleful of the simmering stock to the rice and stir well until absorbed, then continue the process. The rice should be bubbling gently and each addition should be mostly absorbed before more stock is added. After 15-20 mins the rice should be tender with a slight chalky bite. The overall consistency should be saucy but not sloppy – you should be able to see the bottom of the pan when you draw a spoon through it.

Take the pan off the heat and leave to stand for a minute, then vigorously stir in the remaining butter followed by the mascarpone, gruyère and parmesan, then stir with enough vigour that you hear the rice slapping against the side of the pan. Keep on stirring until the butter and cheese have melted together and the stock is thick and oozing. Serve the risotto ladled into warm bowls, topped with the shards of cheese crust and a drizzle of truffle oil, if using, plus a good grinding of black pepper.