Wash and peel the asparagus, cut off the woody ends briefly. Bring 1/2 litre of salted water to the boil. Season with some sugar and a slice of lemon. Let the asparagus peel in it at medium heat for about 20 minutes.
In the meantime, wash the potatoes and cook for about 20 minutes. Then rinse cold, peel and slice. Pour asparagus stock through a sieve. Boil up the liquid again. Cook the asparagus for about 15 minutes, then drain, measure 125 ml of stock and let it cool down.
For the sauce, stir the contents of the bag into cooled asparagus stock. Bring to the boil while stirring, turn off the stove. Cut butter into small pieces and fold in gradually. Heat another 100 ml of asparagus stock, stir in carefully.
Season with salt and pepper. Spread the potato slices in flakes on 4 ovenproof plates. Season with pepper. Wrap 3-4 stalks of asparagus in a slice of cooked ham and spread them on the plates.
(Variation: Cut the rolls 1-2 times.) Spread the sauce as well. Sprinkle with grated cheese and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) until golden brown.