Celeriac Hazelnut Crumble Soup

There's something about the first cool evening of autumn that makes you want to disappear into the kitchen with a bag of celeriac from the market. I'd bought one almost as a dare to myself—that knobby, intimidating root vegetable most people walk right past—and stood there wondering what on earth to do with it. Then came the roasting, the smell of caramelized earthiness filling my tiny flat, and suddenly it clicked: this wasn't going to be just another soup, but something velvety and sophisticated that would actually taste like fall itself.

I made this for my sister during one of those rare rainy Sundays when we both admitted we'd been too tired to cook properly for weeks. Watching her face light up when she tasted it—that moment when comfort food meets genuine surprise—reminded me why I love putting time into these things. She asked for the recipe immediately, then added extra crumble to her bowl like she was rebelling against something.

Ingredients

• Celeriac (about 700 g), peeled and cubed: This is the star, and roasting it first is non-negotiable—it transforms that slightly bitter earthiness into something almost sweet and nutty.
• Medium onion, chopped: Your flavor base, nothing fancy, but don't skip it or the soup will taste one-dimensional.
• Garlic (2 cloves), minced: Just enough to add depth without overpowering the delicate celeriac flavor.
• Medium potato (about 150 g), peeled and diced: This creates body and creaminess naturally, so you can reduce cream if you want.
• Vegetable broth (900 ml): Use good broth if you can—it makes a real difference in the final taste.
• Olive oil (2 tbsp total): Split between roasting and sautéing for gentle, even cooking throughout.
• Heavy cream or plant-based alternative (100 ml): Optional but highly recommended; it softens the earthiness and makes the soup feel luxurious.
• Ground white pepper (1/2 tsp): White pepper is gentler than black and won't speckle your pristine soup.
• Salt, to taste: Taste constantly as you go—seasoning is everything here.
• Hazelnuts (70 g), roughly chopped: Toast them yourself; pre-toasted versions are never quite as alive.
• Unsalted butter or plant-based margarine (1 tbsp): This coats the nuts and makes them sing.
• Sea salt (1/4 tsp): For the crumble specifically—it should taste slightly salty to contrast the soup.
• Fresh parsley, finely chopped (1 tbsp, optional): A small green spark of freshness on top.

Instructions

Get your oven ready and prep the celeriac:

Preheat to 200°C (390°F), then toss your cubed celeriac with a tablespoon of olive oil, salt, and pepper. Spread it all on a baking tray—don't crowd it, or it'll steam instead of roast—and let it sit in the oven for 25–30 minutes, stirring halfway through. You're waiting for that golden, tender-on-the-inside stage.

Start your flavor base while the celeriac roasts:

Heat the remaining tablespoon of olive oil in a large pot over medium heat and sauté your chopped onion for about 4 minutes until it's soft and turning translucent. Add the minced garlic and diced potato, cooking for just another 2 minutes so they get to know the onion.

Build the broth and simmer:

Once your celeriac is golden and tender, transfer it to the pot with the onion mixture. Pour in the vegetable broth and bring everything to a gentle boil, then lower the heat and let it simmer for 15–20 minutes until every vegetable falls apart if you look at it wrong.

Toast the hazelnuts while soup simmers:

In a separate dry skillet over medium heat, toast your roughly chopped hazelnuts for 3–4 minutes, shaking the pan occasionally, until they smell absolutely incredible and turn a deeper brown. Add the butter and sea salt, stirring until the nuts are coated and glossy, then set aside to cool slightly.

Blend until silky smooth:

Using an immersion blender, purée the soup right in the pot in slow, careful passes—or work in batches with a countertop blender if that's what you have. You're aiming for that restaurant-quality velvety texture where nothing grainy remains.

Finish and taste:

Stir in your cream (if using) and taste carefully, adjusting salt and white pepper as needed. This is your moment to trust your palate—the soup should taste balanced and slightly luxurious.

Serve with ceremony:

Ladle the soup into bowls and crown each one generously with your cooled hazelnut crumble and a scatter of fresh parsley. The contrast between warm soup and crunchy, salty nuts is where the magic happens.

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What started as an experiment with a vegetable I barely understood has become one of those recipes I pull out whenever I need to feel capable in the kitchen. There's something grounding about making food this simple taste this good.

Why Celeriac Deserves Your Attention

Most people treat celeriac like an obstacle instead of an opportunity, but once you roast it and taste that concentrated, almost caramel-like earthiness, you understand why it's been a European staple for centuries. It has this humble dignity about it—nothing showy, but genuinely complex and rewarding if you know how to coax out its best qualities. The potato here isn't filler; it's a silent partner that amplifies the celeriac's natural creaminess without adding dairy.

The Hazelnut Crumble Difference

I learned this trick from watching a French chef work and never forgot it: the best soups aren't complete until something breaks the monotony of texture. That toasted, buttery crumble does more than just add crunch; it introduces a warm, nutty flavor that echoes and deepens the earthiness of the celeriac, making them feel like they were destined to meet. The moment you add salt to those hazelnuts, they transform from just toasted nuts into something almost savory, almost like a luxe garnish you'd find on a tasting menu.

Making It Your Own

This recipe is forgiving enough to bend to what you have and what you love. A squeeze of fresh lemon juice brightens everything if your mood calls for lightness, and a whisper of fresh thyme adds an herbal note that makes the whole thing feel more intentional. Some nights I add a tiny pinch of nutmeg to the finished soup—just enough that no one can identify it, but everyone says it tastes incredible.

• If dairy isn't your thing, plant-based cream works beautifully and doesn't change the final flavor one bit.
• You can make the hazelnut crumble up to a day ahead and store it in an airtight container so assembly is instant.
• This soup actually improves if you make it a day or two early and let the flavors deepen in the fridge.

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This is the kind of soup that makes you feel like you've done something meaningful in the kitchen, even though you're mostly just letting the oven do the work. Serve it with crusty bread and someone you like, and watch how quiet the table gets.

Recipe FAQs

→ Can I make this soup ahead of time?

Absolutely. The base soup keeps refrigerated for up to 3 days and freezes well for 3 months. Add the hazelnut crumble fresh just before serving to maintain its crisp texture.

→ What can I substitute for celeriac?

Parsnips or cauliflower work nicely, though celeriac's distinct earthy flavor is irreplaceable. Combination of half parsnip, half potato offers similar creaminess.

→ Is roasting necessary or can I boil everything?

Roasting caramelizes celeriac's natural sugars, adding depth you won't get from boiling alone. It's worth the extra step for significantly richer flavor.

→ Can I use other nuts for the crumble?

Yes, toasted walnuts or pecans complement celeriac beautifully. Keep the butter and salt seasoning—the same technique works for any nuts you choose.

→ How do I achieve the silkiest texture?

Blend thoroughly with an immersion blender or countertop model. Adding the potato helps naturally thicken and smooth the purée without excessive cream.

→ What wine pairs well?

A dry Pinot Gris or Chardonnay cuts through the creamy texture while complementing the earthy, nutty notes. Sauvignon Blanc's acidity also works nicely.