Drain the soaked butter beans and place in a large pan of salted water. Bring to the boil and simmer until soft – the length of time will depend on the age of the beans, but check them after 30 minutes. Once tender, drain and set aside

Sweat the shallots in a little olive oil until translucent. Add the beans, bay leaves and vegetable stock. Bring to a simmer and cook for 15 minutes, then strain (reserving the cooking liquor). Discard the bay leaves

Reserve around 60g of the beans for the casserole, then place the rest into a blender. Blitz until smooth, adding enough of the reserved cooking liquor to create a thick soup consistency. Season to taste and place in a pan to reheat before serving

For the casserole, gently cook the guanciale in a little olive oil in a large saucepan. Add the parsley stalks and mussels (discarding any mussels which don’t close when tapped), then pour in the Manzanilla sherry. Cover with a lid and leave for a few minutes to cook, until the mussels have opened up

Once the mussels are cooked, lift them out of the pan and discard any that haven’t opened. Pick the meat from the shells and return to the pan with the guanciale. Lift out the parsley stalks and blitz with most of the grelot onion and a little olive oil for dressing later

To serve, gently reheat the soup and divide between serving bowls. Combine the mussels and guanciale with the reserved beans, sourdough and diced lemon. Spoon the casserole along one side of the soup, then garnish with finely sliced spring onion and drizzle with olive oil and the blitzed parsley and onion oil to finish