Peel and slice the radish and onion into bite-sized pieces.
Melt butter in a pot and sauté the radish and onion.
Add water to the sautéed ingredients and boil until the radish is tender.
Blend all the ingredients in a blender until smooth.
Pour the blended mixture, milk, and fresh cream into the pot and bring to a boil.
Season with salt and pepper to taste.
Pour the finished soup into a bowl.