Before assembling this dish, start with the preparation of the béchamel sauce. Pour the milk into a sauce pan and bring to the boil together with the studded onion (the onion should be slightly slit and the bay leaf pushed inside and studded with the cloves)Melt the butter in a small saucepan and mix in the flour. Cook briskly over moderate heat. Gradually pour in the warm milk, mixing well after each addition so that you don’t get any lumps. Continue pouring the milk until you obtain a dense thick sauce. Continue to cook for further 5 minutes stirring continuously. Take off the heat and season with the nutmeg and half of the cheese. Meanwhile Blanche the cauliflower in plenty of boiling salted water, taking care not to overcook. Drain and slightly crush the cauliflower with a fork. Next, add a spoon of butter and oil into a large frying pan and gently fry the cauliflower pieces until tender. Add in the béchamel, check for seasoning and remove off the heat. Now you can start assembling the lasagna. Pour some of the sauce into the bottom of an oven proof dish and cover with a layer of the lasagna sheets. Sprinkle with some of the remaining grated cheese and mozzarella and repeat the process again to use all the ingredients. Place in a hot oven and cook for 30 minutes at 200`c, or until golden.