Peel and wash the potatoes and slice or slice them thinly. Heat the oil bit by bit in a large coated pan. Fry the potatoes for 6-8 minutes, turning them in portions.
Season vigorously with salt, pepper and 2 teaspoons pizza spice. Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Spread a thin layer of oil on a baking tray. Spread potatoes on it. Pre-bake in a hot oven for about 10 minutes.
In the meantime peel the onion and cut it into rings. Fry the bacon in a pan until crispy. Take out and let drain on kitchen paper. Fry the onion briefly in the bacon fat. Wash and slice the tomatoes.
Grate cheese. Wash the marjoram, shake dry and remove the leaves.
Remove the tray from the oven. Spread onion, bacon, tomatoes and half marjoram on the potatoes. Season with salt and pepper. Sprinkle cheese on top. Bake in the oven at the same temperature for about 10 minutes.
Remove and sprinkle with rest of marjoram.