Celeriac Soup with Hazelnut Crumble

Last winter, my kitchen smelled like roasted earth for three days straight. I had bought an enormous celeriac, misjudging its size dramatically, and refused to let any go to waste. That mistake became this soup, and now I actually buy two at a time just to keep it in regular rotation. Something about that nutty, celery-meets-parsley flavor feels like a warm hug on gray afternoons.

I served this at a dinner party once, trying to impress people who definitely knew way more about food than I did. They went silent after the first spoonful, and for one panicked moment, I thought something was wrong. Turns out they were just trying to figure out what made it taste so complex. The secret was literally just roasting the heck out of everything first.

Ingredients

• 1 large celeriac: Peeling this knobby beast is the hardest part, but roasting it transforms all that earthy bitterness into something almost sweet
• 1 medium onion: Aromatics are everything, and sauteing this first builds the foundation
• 2 cloves garlic: Add it right before the potato so it does not burn and turn bitter
• 1 medium potato: This is your secret weapon for the silkiest texture without needing tons of cream
• 900 ml vegetable broth: Use one you actually like drinking, because it makes up most of the flavor
• 2 tbsp olive oil: One for roasting, one for sauteing
• 100 ml heavy cream: Totally optional, but it does make everything feel more luxurious
• 1/2 tsp ground white pepper: Black pepper works too, but white disappears into the soup visually
• Salt: Taste repeatedly, because celeriac needs a fair amount to really shine
• 70 g whole hazelnuts: Roughly chop these so some pieces stay sizable for crunch
• 1 tbsp unsalted butter: This coats the nuts and helps them get properly golden
• 1/4 tsp sea salt: Flaky salt on the crumble is not just garnish, it is essential
• 1 tbsp fresh parsley: Brings a little brightness and color to an otherwise very beige situation

Instructions

Roast the celeriac first:

Preheat your oven to 200°C and toss those peeled cubes with olive oil, salt, and pepper until coated. Spread them on a baking tray without overcrowding, then roast for 25 to 30 minutes, turning halfway, until they are soft and starting to turn golden in spots.

Build the flavor base:

While the celeriac roasts, heat another tablespoon of olive oil in a large pot over medium heat. Add the chopped onion and saute for about 4 minutes until it turns translucent and smells sweet. Toss in the garlic and potato, cooking for another 2 minutes to soften them slightly.

Simmer everything together:

Transfer those beautifully roasted celeriac cubes into the pot with the onion mixture. Pour in the vegetable broth and bring it to a gentle boil, then lower the heat and let it simmer for 15 to 20 minutes until all the vegetables are completely tender.

Make the hazelnut magic:

Toast the hazelnuts in a dry skillet over medium heat for 3 to 4 minutes, shaking the pan frequently until they smell nutty and fragrant. Add the butter and sea salt, stirring until the nuts are glossy and golden, then remove from heat and let them cool slightly.

Blend until silky:

Use an immersion blender right in the pot, or work in batches with a regular blender, to puree the soup until it is completely smooth. Stir in the cream if you are using it, then taste and adjust the salt and pepper as needed.

Bring it all together:

Ladle the hot soup into bowls and top each portion generously with that buttery hazelnut crumble. Scatter some fresh parsley over the top and serve immediately while everything is still warm.

Save

My partner, who claims to hate soup, ate three bowls the first time I made this and asked when I was planning to make it again. Something about the combination of velvety smooth base and that crunchy, salty topping just works on every level.

Making It Your Own

Sometimes I throw in a sprig of thyme or rosemary while the vegetables simmer, removing it before blending. The herbal undertone plays so nicely with the celeriacs natural flavor, especially on rainy days when you need something extra comforting.

Serving Suggestions

A dry white wine like Pinot Gris cuts through the richness beautifully. I have also served this with a simple green salad dressed in something acidic to balance the earthy soup. Crusty bread is nonnegotiable for soaking up every last drop.

Batch Cooking Success

This soup freezes surprisingly well, though the hazelnut crumble is definitely best made fresh. I usually make a double batch of the soup base and keep portioned containers in the freezer for those nights when cooking feels impossible.

• Blend in the cream after freezing and reheating for the best texture
• Keep the hazelnuts stored separately so they stay crunchy
• Add a squeeze of lemon right before serving to wake up the flavors

Save

There is something deeply satisfying about turning such an unassuming vegetable into something this elegant and comforting.

Recipe FAQs

→ What does celeriac taste like?

Celeriac has a mild, earthy flavor with subtle celery notes and a hint of sweetness. When roasted, its natural sugars caramelize, creating a deeper, nuttier taste that's less assertive than raw celery.

→ Can I make this soup ahead of time?

Absolutely. The soup base keeps well in the refrigerator for 3-4 days and freezes beautifully for up to 3 months. Store the hazelnut crumble separately and toast just before serving to maintain its crispy texture.

→ What can I substitute for hazelnuts?

Walnuts, pecans, or toasted pumpkin seeds work wonderfully as alternatives. Each brings a slightly different flavor profile while maintaining that essential crunch contrast against the smooth purée.

→ Why roast the celeriac instead of boiling it?

Roasting concentrates celeriac's natural sugars and develops caramelized notes that boiling cannot achieve. This extra step creates a more complex, savory depth in the final purée.

→ How do I achieve the smoothest texture?

Blend thoroughly with an immersion blender or countertop blender until no lumps remain. Adding the potato helps create creaminess, and straining through a fine-mesh sieve ensures an ultra-silky finish if desired.

→ Is the cream necessary?

No—the soup is velvety even without dairy thanks to the potato and thorough blending. The cream adds luxurious richness, but the purée remains satisfying and silky when omitted for a lighter version.