Wash the asparagus and cut off the woody ends. Cut the asparagus into pieces about 5 cm long and cook in boiling salted water for 8-10 minutes. In the meantime, cut ham into strips.
Bring butter sauce and 1/8 litre water to the boil while stirring. Remove from the heat and stir for about 1/2 minute. Season to taste with lemon juice and nutmeg. Grate cheese and stir in. Drain asparagus pieces.
Put the asparagus and ham in a flat casserole dish. Pour sauce over it and bake in the preheated oven (electric cooker: 250°C/ gas: level 5) for approx. 10 minutes. Wash the parsley, dab dry, chop and sprinkle over the asparagus.