For the celery soup with chestnuts, peel and dice the celery, finely chop the shallot and sauté with the celery in the heated butter until colorless, add the chestnuts to the pot and sauté briefly.
Pour in the soup and add the bay leaf. Season with salt and pepper. Cover the soup and simmer for about 30 minutes until the celery and chestnuts are soft.
Then add the cream to the soup and blend everything with a hand blender to a fine creamy soup. Season if necessary and serve garnished with thyme leaves.