Wash the potatoes and cook in water for about 20 minutes. In the meantime, clean and wash the mushrooms and, depending on their size, possibly halve them. Clean, wash and cut spring onions into rings, wash and chop oregano. Cut the smoked pork loin into small cubes. Heat oil.
Sauté the mushrooms in it over high heat. Season with salt and pepper. Sauté the sausage briefly. Dust with flour and sauté. Add stock, milk and cream while stirring constantly, bring to the boil. Stir in spring onions and oregano, season again. Drain potatoes, rinse with cold water and peel. Fill potatoes and vegetable casserole mixture into an ovenproof dish. Grate the cheese and sprinkle over it.
Stir in spring onions and oregano, season again. Drain potatoes, rinse with cold water and peel. Fill potatoes and vegetable casserole mixture into an ovenproof dish. Grate the cheese and sprinkle over it. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 20 minutes until golden brown. Sprinkle with chive rolls and serve garnished with fresh oregano leaves