Put leaf spinach with 100 ml water in a pot. Cover and allow to defrost at medium heat while stirring occasionally for about 15 minutes. In the meantime, wash the cutlets and dab dry with kitchen paper.
Season with salt and pepper. Heat 2 tablespoons of oil in a frying pan, fry the escalopes in it for about 2 minutes on each side. Peel and finely dice the onion. Sauté onion in 1 tablespoon of oil, add 250 ml water and bring to the boil.
Stir in sauce powder with a whisk and let it boil for about 1 minute. Wash, clean and slice the tomatoes. Drain the spinach. Wash parsley, dab dry and chop finely.
Mix spinach with parsley, season with salt and pepper. Spread the spinach in a casserole dish. Put the schnitzel on top, spread the tomatoes on top. Pour sauce over it and sprinkle everything with cheese. Bake in a preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for 5-8 minutes.