Peel the asparagus. Cut off the wooden end and cook in a little salted water with sugar and lemon juice until firm to the bite. Take the asparagus out of the water and set aside 150 ml of the asparagus water.
Melt the butter in a pan, add the onions and sauté until translucent, deglaze with the asparagus water and reduce a little. Add the cream and let simmer briefly.
Cut the asparagus 2 to 3 cm. Cut long pieces, add to the sauce with the prosciutto, add the herbs, season with salt and pepper, mix well and keep warm on the stove.
Boil the pasta in salted water until firm to the bite, pour off, drain and arrange on 5 plates, pour the sauce over it, sprinkle with a little parmesan and pour over it once with the pepper mill. Serve immediately!