Defrost the spinach. For the tomato sauce, peel and chop the onions and garlic. Heat 2 tablespoons of oil in a saucepan. Fry the garlic and half of the onion cubes in it. Add tomatoes and oregano.
Season with salt, pepper and sugar. Bring to the boil and simmer open for about 10 minutes. Season to taste with salt, pepper and sugar.
For the cheese filling, heat 1 tablespoon of oil. Fry the rest of the onion cubes in it until golden brown, let it cool down. Coarsely grate the mountain cheese, mix half with the onions. Finely dice the mozzarella. Remove the bread roll from the packaging.
Press each roll in the middle and fill it with some onion-cheese mixture (see fig. 1). Press the dough over it.
Place the rolls in a greased round ovenproof dish (approx. 28 cm Ø). Squeeze the spinach. Spread the spinach and tomato sauce on the rolls. Sprinkle with mozzarella and the rest of the mountain cheese. In a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see
manufacturer) bake for about 45 minutes. Cover if necessary after approx. 30 minutes. Salad tastes good with it.