For the cauliflower casserole, blanch the cleaned and quartered cauliflower in boiling salted water for about 15 minutes.
Then rinse with cold water, drain well. Roughly cut out the stalk and divide into florets.
Cut ham into cubes and brown in butter. Put cauliflower and ham in a greased baking dish and mix together.
Make a light roux with butter and flour, deglaze with milk. Season the sauce with salt, pepper, nutmeg and spread over the casserole ingredients. Sprinkle with grated cheese.
Cook in preheated oven (220 degrees) for about 20 minutes.