For the potato casserole, peel the potatoes and boil them in salted water until soft, strain. Make a mash from the potatoes, milk and butter. Season with salt, pepper and nutmeg and set aside.
Heat the oil in a large frying pan, sauté the onion cubes until translucent and add the mince. Add a dash of wine. Cut the dried tomatoes into pieces and add them. Add chopped garlic and herbs. Fry for a few minutes and season with salt and pepper.
Grease a gratin dish with a little butter. Now alternate layers of minced meat and mashed potatoes. The casserole should end with a layer of mashed potatoes. Sprinkle grated cheese and butter flakes on top. Bake for 25 to 30 minutes in the oven at 200° Celsius. Towards the end, grill briefly.
Before serving, let the potato casserole cool briefly, then it is easier to portion.