Wash the mugwort thoroughly and prepare it.
Dice the potatoes and onions.
Melt the butter in a pot and sauté the onions.
Add the potatoes and mugwort, then stir-fry together.
Pour in water and boil until the ingredients are cooked.
Blend everything until smooth in a blender.
Return to the pot and add the milk and heavy cream, simmer until creamy.
Season with salt and pepper.
Serve warm in a bowl.