Celeriac Soup With Hazelnut Crumble

There's something about celeriac that catches you off guard the first time you really cook with it. A friend handed me one at a farmer's market with this knowing look, saying I absolutely had to roast it, and I stood in my kitchen wondering what I'd gotten myself into with this gnarly, oversized celery root. But forty-five minutes later, when that oven opened and released this sweet, almost nutty aroma, I understood the hype. Now this soup appears on my table whenever autumn gets serious, and the hazelnut crumble on top has become non-negotiable.

I made this for my sister's impromptu dinner party when she called panicking about what to serve to unexpected guests, and watching her face when everyone asked for the recipe was worth the slightly frantic afternoon of prep. She's not even a soup person, but something about the combination of velvety warmth and textural contrast had everyone at that table leaning in for another spoonful. It became the thing people actually remembered about that night.

Ingredients

• Celeriac (700 g), peeled and diced: This is the star of the show—roasting it mellows its earthiness and brings out a subtle sweetness that makes the whole soup sing.
• Onion and garlic (1 medium onion, 2 cloves): The aromatics that build flavor depth while the celeriac roasts, creating that savory base everything else builds on.
• Potato (150 g), peeled and diced: This adds body and creaminess to the soup without needing excessive cream, a trick I learned from accidentally making a thinner batch once.
• Vegetable broth (900 ml): Use a quality broth you'd actually drink on its own—it makes a noticeable difference in the final taste.
• Olive oil (2 tbsp total): One tablespoon goes to the celeriac for roasting, the other starts your aromatics—this split matters more than you'd think.
• Heavy cream (100 ml, optional): A splash at the end softens the earthiness, though the soup is equally beautiful without it if you're keeping things plant-based.
• Sea salt, black pepper, and ground nutmeg: The nutmeg is your secret weapon—just a quarter teaspoon adds a warmth that makes people ask what that mysterious note is.
• Hazelnuts (60 g), whole: Choose raw hazelnuts if you can find them; toasting them yourself gives you control over how golden they become.
• Unsalted butter (1 tbsp): For the crumble toasting—olive oil works too if you want to keep everything plant-based.
• Fresh parsley (1 tbsp, finely chopped): Stirred into the warm hazelnut crumble, it adds color and a bright herbal note that cuts through the richness.

Instructions

Preheat and roast the celeriac:

Set your oven to 200°C (400°F). Spread the diced celeriac on a baking sheet, drizzle with 1 tablespoon of olive oil, toss until every piece is coated, and let it roast for 25–30 minutes, turning once halfway through. You'll know it's ready when the edges turn golden and the pieces feel tender when pierced with a fork—this is when the magic happens flavor-wise.

Start your aromatics while everything roasts:

Heat the remaining 1 tablespoon of olive oil in a large pot over medium heat. Dice your onion and mince your garlic, then add them to the pot, stirring occasionally for 3–4 minutes until softened and fragrant. This is your flavor foundation, so let them get a little golden if you have time.

Build the soup base:

Once the celeriac is golden and tender, add it to the pot along with the diced potato. Pour in your vegetable broth and bring everything to a boil, then lower the heat and let it simmer gently for 15–20 minutes. The vegetables should be completely soft and almost falling apart—this is when they're easiest to blend smoothly.

Toast the hazelnuts for crumble:

While the soup simmers, roughly chop your hazelnuts and melt the butter in a small skillet over medium heat. Add the hazelnuts and toast them for 2–3 minutes, stirring frequently, until they smell toasty and golden. Remove from heat, stir in the chopped parsley and a pinch of sea salt, then set aside to cool slightly.

Blend until silky smooth:

Once the soup vegetables are tender, use an immersion blender to puree everything until completely smooth, working directly in the pot. If you prefer using a stand blender, work in batches and return the puree to the pot—just be careful with hot liquids.

Season and finish:

Stir in the cream (if using), ground nutmeg, sea salt, and freshly ground black pepper. Taste as you go—you might need a touch more salt depending on your broth. If everything has cooled during blending, reheat gently over low heat until steaming.

Serve with ceremony:

Ladle the soup into bowls and crown each one with a generous handful of the hazelnut crumble. Serve immediately while both the soup and crumble are at their best texturally.

Save

My neighbor tasted this soup last winter and started growing celeriac in her garden the following spring, just so she could make it whenever she wanted. There's something about watching someone else fall in love with a dish you've made that changes how you feel about cooking it yourself.

The Roasting Step Is Everything

I learned this the hard way when I once tried to rush things by skipping the oven and just boiling the celeriac raw. The soup was technically fine, but it tasted like celery—flat, grassy, forgettable. The moment I committed to the roasting step, everything shifted. That oven time caramelizes the natural sugars in the celeriac and deepens the flavor into something almost nutty and sweet, which is why people keep asking if there's something special hidden in the recipe. There isn't—it's just that small decision to honor the ingredient by treating it right.

Making It Vegan or Dairy-Free

I've made this soup for friends with different dietary needs, and honestly, it doesn't lose anything in translation. Swap the heavy cream for a good plant-based alternative—oat cream works beautifully if you have it—and use olive oil instead of butter for toasting the hazelnuts. The soup remains velvety and the crumble remains crunchy, and no one sitting at the table would guess it's different from the original. Sometimes the simplest ingredient swaps prove that the dish itself is what matters, not the specific fats holding it together.

Pairing and Serving Suggestions

This soup deserves company at the table, which is why I always plan ahead to pair it with something that enhances rather than competes. Crusty bread is non-negotiable—something with a real crust that you can tear and use to capture the last silky bits at the bottom of your bowl. A crisp white wine like Sauvignon Blanc cuts through the richness beautifully, and I've learned that the acidity in the wine makes you taste all the subtle notes in the soup even more clearly.

• If you want to gild the lily, drizzle finished bowls with hazelnut oil instead of plain olive oil for an extra layer of nuttiness.
• A shower of extra fresh parsley or even a few microgreens adds color and freshness that balances the earthiness.
• Serve this soup when you want people to slow down and actually taste what they're eating, not when you're feeding a crowd in a hurry.

Save

This soup has become my quiet anchor dish, the one I make when I want to remember why I love cooking in the first place. There's something about starting with a gnarly root vegetable and ending with something velvety and comforting that feels like a small kitchen victory every single time.

Recipe FAQs

→ Can I make this ahead of time?

Absolutely. The soup base keeps well in the refrigerator for up to 3 days. Store the hazelnut crumble separately in an airtight container and sprinkle it fresh when serving. Gently reheat the soup over low heat, adding a splash of broth or cream if it thickens too much.

→ What can I substitute for hazelnuts?

Walnuts, pecans, or toasted pumpkin seeds work beautifully as alternatives. Each brings its own nutty profile and crunch. For a nut-free version, try crispy fried shallots or homemade croutons with herbs.

→ Is roasting the celeriac necessary?

Roasting isn't strictly required, but it elevates the dish significantly. The high heat caramelizes the celeriac's natural sugars, adding depth and sweetness that boiling alone can't achieve. If pressed for time, you can simmer raw diced celeriac directly in the broth for 25-30 minutes until tender.

→ How do I achieve the smoothest texture?

Simmer vegetables until completely tender—they should yield easily to a fork. Use an immersion blender for 2-3 minutes, or a high-speed blender in batches. For restaurant-smooth results, pass the purée through a fine-mesh sieve after blending. The potato helps create that silky consistency.

→ Can I freeze this soup?

Yes, freeze the soup base without cream for up to 3 months. Thaw overnight in the refrigerator, reheat gently, and stir in fresh cream along with seasonings. The hazelnut crumble freezes well too—toast it again briefly at 180°C for 3-4 minutes to restore crunch before serving.

→ What pairs well with this soup?

Crusty sourdough or country bread is ideal for soaking up every drop. A crisp white wine like Sauvignon Blanc or Chablis cuts through the richness beautifully. For a complete meal, serve alongside a simple green salad with vinaigrette.