Rinse the asparagus, snap off the tough and thick ends (about 3 cm), peel the stalks, cut into 2 cm pieces. The tough ends can be used to make vegetable broth, they are fibrous and are not suitable for blending in the soup.
In a pot, melt 2 tablespoons of butter and sauté the diced onion until golden. Then add the peeled and finely diced potatoes and sauté stirring occasionally for about 5 minutes.
Add the asparagus (except the tips) and 2 tablespoons of butter and sauté stirring occasionally for 1–2 minutes. Season with salt, nutmeg and mix.
Pour in the hot broth and bring to a boil. Simmer for about 5 minutes, then add the asparagus tips and cook for another 2 minutes. Blend in a standing blender with the addition of heavy cream to a perfectly smooth cream (about 1 minute of blending), reserving a few asparagus tips for garnish.
The soup can additionally be strained through a sieve and the pulp collected on the sieve pressed with a spoon, thus removing the fibrous bits of asparagus. Add half a teaspoon of finely ground pepper to the soup and reheat on low heat before serving. Serve with bacon chips and grated nutmeg and optionally with watercress or arugula.