Wash and clean the cauliflower and soak in cold salted water for 30 minutes. Then cook in fresh, lightly salted water for 15 minutes. Then put in a greased baking dish. Cut the boiled potatoes into slices and place them around the cauliflower. Add the diced ham and chopped parsley.
For the sauce, heat the margarine and fry the peeled and diced onions until golden. Stir in the flour and top up with milk and meat stock. Let the sauce simmer for 7 minutes, then season with salt and paprika.
Mix the cream with the egg yolk and whisk into the sauce. Now pour the sauce over the cauliflower and sprinkle with cheese. Put the mold in the preheated oven and bake at 220 degrees for 15 minutes.