Peel and finely dice the onions and garlic. Wash the zucchini. Clean the mushrooms and clean them. Peel and wash carrots. Quarter peppers, remove seeds and wash. Dice zucchini, mushrooms, carrots and peppers evenly.
Heat oil in a pan, add onions and garlic, sprinkle with sugar and sauté in it. Add vegetables and fry for about 5 minutes. Add tomatoes, bring to the boil and season with salt and pepper.
Stir in dried herbs. Heat fat, sweat flour in it and deglaze with broth and milk. Cook for about 5 minutes and stir in 50 g cheese. Remove from heat, season with salt, pepper and nutmeg.
Alternate layers of béchamel sauce, lasagne dishes and vegetables in a greased casserole dish (approx. 2 litres). Finish with lasagne platters and vegetables. Sprinkle 75 g cheese on top. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 35 minutes.
Serve garnished with marjoram.