Clean and wash Brussels sprouts and cook in salted boiling water for about 15 minutes. Remove with the slotted spoon, keep 150 ml of the cooking water. For the sauce, melt the butter, stir in the flour and sweat.
Add the Brussels sprouts water and milk and bring to the boil while stirring. Let simmer gently for 10 minutes. Then stir in the cheese and let it melt. Season heartily with wine, salt, pepper and nutmeg. Roughly chop the parsley, add to the sauce, pour over the Brussels sprouts. Serve the ham with it.