Wash the cauliflower, separate the florets and parboil them for about 10 minutes in hot water. Then drain them and place them in a casserole dish.
Melt the butter in a pan and add the flour and milk, stirring constantly to avoid clumps. Season the béchamel sauce with salt, pepper, and nutmeg.
Next, add the cheddar and mozzarella to the sauce and stir for as long as it takes for all the cheese to melt. Then pour the sauce over the cauliflower.
Halve the slices of ham and roll them into little roses, and stick them in between the cauliflower florets. Now bake the casserole for 12 minutes at 375°F.