60g / 4 tbsp unsalted butter

2 garlic cloves, finely chopped

1 onion, diced (brown or yellow)

1/2 leek (white part only), diced into 1cm cubes (~3/4 cup)

3 celery stems, diced into 1cm cubes (~1 1/2 cups)

800g / 1.6 lb peeled celeriac, cut into 2cm cubes (~1kg / 2lb unpeeled)

200g / 7oz potato, peeled and cut into 2cm cubes (about 1 large)

1.5 litres / 6 cups water or stock

1 1/2 tsp salt

1/4 tsp white pepper

1 cup full-fat cream (pure, thickened, or heavy)

1 bay leaf

2 thyme sprigs

1/2 tsp black peppercorns

1/2 tsp coriander seeds (or 1/8 tsp powder if no sachet)

Croutons

Olive oil, for drizzling

1 tbsp chives, finely chopped (or parsley/chervil)

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Make a spice sachet by bundling the bay leaf, thyme, peppercorns, and coriander seeds in a small piece of cheesecloth tied with kitchen twine.
Melt butter in a large pot over medium-low heat. Add onion, leek, celery, and garlic. Cook gently for about 10 minutes until softened but not browned.
Add celeriac and potato, stirring frequently for 10 minutes until slightly softened, keeping the mixture pale.
Pour in water or stock, then add salt, white pepper, and the spice sachet. Bring to a boil, reduce heat, and simmer uncovered for 25 minutes until celeriac is tender.
Stir in the cream and simmer for another 3 minutes.
Remove the spice sachet and blend the soup until perfectly smooth using a stick blender or a high-speed blender in batches.
Taste and adjust seasoning with more salt or pepper if needed.
Ladle into bowls, top with croutons, drizzle with olive oil, and sprinkle with chives before serving.

Use vegetable stock instead of water for a deeper flavor.

For a lighter version, replace cream with evaporated milk or omit it entirely.

To make it vegan, use olive oil instead of butter and coconut or cashew cream in place of dairy cream.

Keep the heat low to maintain the soup’s pale color and prevent browning.

The soup can be made ahead and reheated gently before serving.