Clean the cauliflower. Cook in salted boiling water for 8-10 minutes until tender. Drain well. Peel the onion and cut into cubes. Wash the parsley, pat dry, and chop finely.
Clean and wash the tomatoes, then cut into slices. Sprinkle with salt and pepper.
In a bowl, combine the minced meat, cubed onion, chopped parsley, and 1 egg. Season with salt, pepper, and nutmeg. Refrigerate until assembly.
Grease an ovenproof casserole dish. Place the drained cauliflower stalk-side down in the center. Arrange tomato slices around the cauliflower. Dot with butter. Spread the minced meat mixture over the tomatoes.
In a bowl, whisk together the remaining 2 eggs, cream, and grated cheese. Season with salt, pepper, and nutmeg. Pour the cream mixture over the cauliflower and minced meat.