Drain corn and tuna separately. Clean, wash and chop the spring onions. Heat the oil in a pan and fry the spring onions for 2-3 minutes at low heat. Clean, wash and cut the tomatoes into eighths. Roughly cut the tuna into pieces and mix it with the corn, spring onions and tomatoes and put it into an ovenproof dish. For the sauce heat 20 g fat.
Dust with flour and let it sweat on. While stirring, deglaze with stock and cream and bring to the boil. Grate cheese finely, add to the sauce and let it melt in it. Spread over the vegetable-tuna mixture and sprinkle with breadcrumbs. Spread the remaining fat as flakes on top and bake in a preheated oven (electric range: 200 °C/ gas: level 3) for 10-15 minutes. Serve garnished with parsley as desired