Prepare a fish stock using also the shell of the fish to make it more savoury. Add the chopped onion, celery, carrots and the wild cicely stalks. Chop another onion. Melt half of the butter in a saucepan, add the onion and cook for 5 minutes until soft and golden. Add in the chopped lobster and the rice and sauté for a few minutes to acquire flavour. Add the wine and cook until the alcohol is evaporated. Add a ladleful of stock and coninue adding it a ladleful at a time until the rice is tender. Add the remaining butter and stir in the grana padano cheese. Serve immediately.