Heat olive oil and butter in a large pot.

Add finely chopped onion. Fry for 5 mins.

Cut woody ends off asparagus. Chop. Put heads aside for garnish.

Pour stock into pot and add asparagus. Boil covered for 10–15 mins. Asparagus is done when as soft as boiled potatoes.

Put pot aside and sprinkle the soup with a pinch of ground nutmeg. Take a hand blender and mix soup until smooth.

Serve topped with roasted asparagus heads.