Wash the potatoes thoroughly and cook them with the skin in water for about 20 minutes. Drain the potatoes, rinse in cold water, peel and let cool, then cut into slices.
In the meantime, peel the onion and garlic and cut into fine cubes. Heat the oil in a pan and fry the minced meat in it until crumbly. Add the onion and garlic and fry briefly. Stir in tomato paste and sweat a little. Deglaze with the tomatoes, sprinkle with herbs and simmer for about 5 minutes. Season well with salt and pepper.
Dissolve the vegetable stock in the hot water. Melt the butter in a saucepan, add the flour and sweat. Gradually stir in the vegetable stock and milk and simmer for about 10 minutes, stirring occasionally. Finely chop the parsley and stir in.
Peel and wash the carrots, clean and wash the zucchini. Cut both into slices.
Preheat the oven to 200 ° C or 175 ° C fan oven.
Grease a 1.2 l casserole dish and alternately layer the potato slices, the minced meat and the vegetable slices. Pour the sauce over it and sprinkle the grated cheese over the casserole.
Bake for 30-35 minutes and garnish with sage and thyme if you like.