Peel the garlic, press through a garlic press and beat with milk, eggs, a little salt, pepper and nutmeg. Cut flat bread into half slices and pour the egg milk over them.
Leave to stand for 5-10 minutes. Meanwhile wash the tomatoes, dab dry and cut into slices. Peel and chop the onion. Drain the corn. Heat some fat in an ovenproof pan and fry the bread in portions, turning it over until golden brown.
Place the bread, tomato slices and corn in the pan in a fan shape and sprinkle with onions, salt and pepper. Spread the tuna with the oil on top and finally crumble the feta cheese over it. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 25 minutes.
Wash parsley, dab dry and chop except for something to garnish. Sprinkle the finished pan with parsley and serve garnished.