Peel and wash the carrots and cut them into diagonal slices. Clean, wash and cut broccoli into small florets. Peel onion, cut into thin slices. First blanch the carrots for about 2 minutes in little boiling salted water.
Lift out with a skimmer. Briefly blanch the broccoli and vegetable onion in the vegetable water one after the other. Place the prepared vegetables in ovenproof dishes. Season cream with salt, pepper and nutmeg and pour over the vegetables.
Sprinkle with cheese. Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 15-20 minutes.