Wash the potatoes and cook for about 20 minutes. Clean the leek, wash thoroughly. Halve the sticks. Cover and cook in 600 ml boiling salted water for about 8 minutes. Drain well, catch the cooking water
Sweat flour in hot fat. Stir in 1/2 l cooking water, cream, milk and stock. Bring to the boil, simmer for about 3 minutes. Season to taste
Grate cheese. Drain, quench, peel and slice the potatoes
Peel and chop the garlic. Fry in hot oil in a pan. Add minced meat and fry until crumbly. Season with salt and pepper. Stir in tomato paste and sweat briefly. Add tomatoes and juice, chop a little bit. Bring to the boil and let it boil down for about 5 minutes. Season to taste with salt and pepper
Place the potatoes in a large greased casserole dish. Pour 3/4 béchamel sauce over it. Place the leeks close together and cover with the chopped sauce. Pour the rest of the béchamel sauce over it and sprinkle with cheese. In a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) approx.
Bake for 20 minutes. Sprinkle with parsley