Wash the potatoes and cook in boiling water for about 20 minutes. In the meantime, wash the chicken filet, dab dry and cut into slices of about 3 cm thickness. Wash and clean the broccoli and cut the florets from the stems.
Cook the broccoli florets in boiling salted water for about 5 minutes. Drain and let it evaporate. Heat the oil in a pan and fry the fillet until golden brown. Remove and briefly sauté the garlic in it.
Take it out. Drain potatoes, rinse with cold water and peel. Cut potatoes into slices. Place a layer of potato slices in an ovenproof casserole dish. Layer the remaining potato slices, broccoli and chicken on top.
Wash oregano, except for a little to garnish, dab dry and chop finely. Whisk eggs and cream, season with salt and pepper. Stir in garlic and oregano. Pour egg cream over the casserole.
Grate the Parmesan finely and sprinkle over it. Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 40 minutes. Cover after 20 minutes if necessary. Remove and serve garnished with oregano.