Clean, peel and wash the carrots, halve them lengthwise and cut into slices. Clean, wash and cut leek into rings. Clean, wash and cut cauliflower into florets. Cook in boiling salted water for 6-8 minutes.
Pour off, rinse with cold water and drain. Peel and finely chop the onion. Heat the oil in a pan and fry the minced meat until crumbly. Add the onion and fry briefly. Add tomato paste, sweat off briefly.
Add tomatoes, simmer for 5 minutes at low heat, season with salt and pepper. Melt the fat in a saucepan. Dust with flour and sauté briefly while stirring. Add 350 ml water and milk bit by bit while stirring.
Bring to the boil, stir in the stock. Let simmer for 5 minutes at low heat. Season to taste with salt and pepper. Grease casserole dish. Put half of the minced meat mixture into the baking dish. Spread half of the vegetable mixture on it and pour half of the sauce over it.
Put the rest of the minced meat, vegetables and sauce into the mould. Sprinkle with cheese. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes. Serve garnished with chervil.