Fry the onion and butter soft and golden brown.
Add the broth and boil it. Peel the asparagus or use peeled asparagus.
Cut the asparagus into pieces. Add the pieces to the broth and boil for half an hour.
Puree the soup with a blender and poor it back into the pan.
Optionally you keep a few pieces of asparagus to add in the finished soup.
Add the cream and warm it up for a few minutes.
Add pepper and salt and serve the soup in plates or cups.