Bring 3/4-1 l salted water to the boil. Preheat oven (electric cooker: 225 °C/recirculating air: 200 °C/gas: level 4). Clean, wash and cut leek into large pieces. Cook in salt water for approx. 8 minutes
Peel and chop the onion. Fry with minced meat in hot oil, season. With tomatoes and juice and about 3/8 l water
...to extinguish. Bring to the boil, stir in broth. Chop the tomatoes, boil down for about 5 minutes
Drain the leek. Cut the cheese into slices. Pour sauce into 1 large or 3 small casseroles. Spread leek and cheese on top. Bake in a hot oven for about 10 minutes
Bring 3/8 l water and 1/4-1/2 tsp salt to the boil. Remove from heat. Add milk. Stir in purée. After 1 minute add butter, stir. Serve everything