For the cream of celery soup a la Hildegard, cut the peeled celery into slices and bring to a boil with the water. After boiling, reduce to a simmer. Puree the softly cooked celery.
Prepare a roux with butter, spelt flour and a little celery soup.
Add the rest of the soup and bring to the boil again. Season to taste with salt, pepper and bertram.
Before serving, refine the cream of celery soup a la Hildegard with whipped cream and sprinkle with chopped celery leaves.