Rinse porcini well, boil in milk. Remove from the stove. Peel, wash and chop the potatoes. Cook in salted water for about 20 minutes
Clean or peel and wash the vegetables. Divide cauliflower and broccoli into florets. Cut carrots into slices. Cook carrots and cauliflower covered in about 1/2 l boiling salted water for 10-12 minutes. Cook broccoli for about 5 minutes. Drain the vegetables, collect the vegetable water
Clean, wash and halve the mushrooms. Peel and chop onion. Fry in 2 tablespoons of hot butter in a large pan. Brown the mushrooms. Season with salt and pepper. Add flour, sweat. Stir in vegetable water and cream, bring to the boil. Simmer for about 5 minutes. Grate cheese, melt 1/3 in the sauce. Season to taste. Add vegetables to the sauce
Drain and mash the potatoes. Stir in 1 tablespoon butter and porcini milk. Season with salt and pepper. Grease large casserole dish. Fill in the purée as a rim, spread the vegetables in the middle. Sprinkle with the rest of the cheese. Gratinate in the preheated oven (electric cooker: 250 °C/circulating air: 225 °C/gas: level 5) for about 10 minutes.
Drink: cool white wine