Clean and wash the cauliflower and broccoli and divide into florets. Peel, wash and cut carrots into pieces. Cook the cauliflower for 10 minutes in plenty of boiling salted water. Add broccoli florets and carrots after 5 minutes and cook.
Wash Bulgur cold and boil in 200 ml salted water. Let it swell for about 10 minutes at low heat. Drain the vegetables, collect the cooking water and let it cool down a little. Mix 1/2 litre vegetable water and Fix for broccoli gratin in a pot.
Bring to the boil while stirring and simmer for 1 minute. Grate cheese. Put the vegetables and bulgur in an ovenproof dish. Pour sauce over them. Sprinkle with cheese and bake in a preheated oven (electric: 175 °C/ gas: level 2) for about 20 minutes.
Wash parsley, dab dry and chop. Sprinkle over the casserole.