Celeriac and Le Gruyère AOP agnolotti

If making the parsley oil, place the parsley and oil in a high-powered blender and blitz for 5-10 minutes, until the oil has heated up due to the friction of the blades and turned bright green. Strain the oil through muslin cloth into a bowl overnight in the fridge

To prepare the celeriac, preheat an oven to 180°C/gas mark 4. Mix the rock salt and flour in a bowl, then slowly add enough water to create a dry but workable dough. Wrap the celeriac with this mixture, ensuring it is fully sealed, then place in the oven and cook for 90 minutes

While the celeriac cooks, make the pasta dough. Place the flour in a food processor and, with the motor running, slowly add the egg, egg yolks, salt and olive oil. Pour in a little water to just bring the dough together, then turn out onto a floured work surface and knead for 10 minutes until smooth. Wrap the pasta dough in cling film, then place in the fridge for at least 1 hour to rest

Once the celeriac has been cooking for 90 minutes, remove it from the oven and leave to cool for 1 hour

While the celeriac cools, prepare the sauce. Place the milk and cheese in a saucepan and very gently heat, allowing the cheese to melt. Keep the milk warm but do not let it simmer or boil. Once the cheese has fully melted and the milk has taken on its flavour, leave the milk to strain through a muslin cloth into a clean saucepan

Break off the salt crust from around the cooled celeriac, peeling off the skin at the same time. Cut a few thick slices from the centre of the celeriac and use a 3cm ring cutter to stamp out 16 small discs, then set these aside for later

Transfer the remaining celeriac to a blender and blitz to a rough purée. Add the Gruyère, brown butter, lemon juice, chives and parsley and blitz again to combine (or simply stir them through). Transfer this mixture to a piping bag

Unwrap the pasta and feed it through a pasta machine, starting on the widest setting and gradually working down to the thinnest, cutting it into sheets if needed. Lay the thin pasta sheets out on a work surface dusted with flour, trimming them into similar shaped rectangles. Pipe a line of the celeriac purée along the bottom of each sheet of pasta, then fold the pasta over the top, rolling it around the mixture to ensure it is fully sealed. Using your thumb and finger, pinch the pasta every 5cm along to create individual parcels, then use a pasta wheel to cut each one into individual agnolotti. Repeat this process until you have used up all the pasta and filling, and are left with a pile of agnolotti

Once the milk has finished draining through the muslin cloth, blend in the xanthan gum with a stick blender to thicken slightly and set aside to gently reheat before serving

When ready to serve, bring a large pan of salted water to the boil and place a small frying pan over a medium heat. Add a knob of butter to the frying pan along with the mushrooms, then gently fry until just cooked. Finish with the lemon juice and a pinch of salt and keep warm

Meanwhile, plunge the agnolotti into the boiling water and simmer for 3 minutes and place the reserved discs of celeriac into the cheese sauce to gently reheat

To serve, pour a little of the warm cheese sauce in the bottom of each bowl. Place a few celeriac discs in the sauce, then pile the agnolotti on top. Garnish with the mushrooms, Iberico ham and herbs, then drizzle or dot the parsley oil to finish (if using)