Onions: Save 4tsp breadcrumbs, mix the remainder with the milk. Cook the onions in salted water for 30 minutes and then leave the onions to cool in the water. Once cooled, trim the onions tops and bottoms, removing the skin, then take off the top quarter of the onion and retain. Hollow out the centre of the onions leaving two layers. Place the top quarter into the onion to give a firmer base. Chop up the inside centres of the onion and saute them in a pan until lightly browned. Place the saute onion in a food processor with the rest of the ingredients, including the breadcrumbs and milk, and process to a rough paste. Cook in a medium oven with a little water for 30 minutes. Top the onion with the reserved breadcrumbs and a dribble of oil before roasting. Tomatoes: Scoop out the tomato seeds, season and turn upside down to drain on a tray. Combine basil, parmesan, pine nuts, breadcrumbs and garlic in a food processor, blitz then add enough oil to bind the mixture together. Season. Stuff the tomatoes with the mixture, being careful not to overfill. Bake in a slow oven for 40 minutes, add water to the dish from time to time. Garnish with a dribble of olive oil and parsley. Mushrooms: Chop the mushroom stalks finely and heat a little oil in a frying pan, add the shallots and mushroom stalks and sweat until tender. Add the garlic, parsley and breadcrumbs and allow to cool. Mix in a little oil for binding and season. Spoon into the mushroom cups and arrange in a baking tray. Add a few drops of water and bake in a medium oven for 30 minutes.