Prep Time: 40 min
Heat a tablespoon of oil in a large pan. Add the onions and celery and cook over a medium heat for 10 minutes until soft. Remove thyme leaves from stems and add to the pan. Thinly slice 4-6 apple slices away from one quarter to use as a garnish, then add the celeriac and the rest of the apples and cook for 2–3 minutes. Add the stock, season with salt and pepper, and simmer over a low heat for 30 minutes until the celeriac is tender.Remove from the heat and use an immersion blender to blend the soup until smooth. If using a countertop blender, allow the soup to cool before blending. Return to the pan and bring soup back to a low simmer. Stir in half the crème fraîche. To serve, drizzle with olive oil, crème fraîche and apple slices.