Celeriac Soup With Hazelnut Crumble

There's something about autumn that makes me crave earth-toned dishes, and this celeriac soup arrived in my kitchen almost by accident. I'd bought a gnarly celeriac root at the farmer's market thinking I'd roast it, but then discovered a half-empty carton of cream in my fridge and suddenly remembered a soup I'd tasted years ago at a small bistro in Lyon. The combination of sweet roasted celeriac with that unexpected crunch of hazelnuts felt like the perfect way to bridge seasons, turning a humble vegetable into something that tasted far more elegant than the effort required.

I made this for my neighbor last winter when she'd been under the weather, and watching her take that first spoonful—the way her shoulders relaxed—reminded me why comfort food matters. She asked for the recipe that same evening, and now whenever I see her, she mentions how it's become her go-to when she needs something warming and real.

Ingredients

• Celeriac (about 700 g): This knobby, underrated root vegetable develops a subtle sweetness when roasted, becoming the soup's backbone—don't skip the roasting step, it truly matters.
• Onion and garlic: The aromatic foundation that builds flavor quietly in the background while your celeriac gets golden.
• Potato (about 150 g): Added for body and silkiness rather than bulk—it keeps the soup luxurious without making it heavy or starchy-tasting.
• Vegetable broth (900 ml): Use a good quality one if you can; it becomes the voice of the whole dish since everything else is so mild.
• Heavy cream or plant-based alternative: Optional but transformative—just 100 ml makes the texture feel like velvet against your tongue.
• Sea salt, black pepper, ground nutmeg: Nutmeg especially is the secret whisper here, grounding the sweetness and making people wonder what that mysterious note is.
• Hazelnuts (60 g): Raw hazelnuts toasted in butter become fragrant and golden, providing textural contrast and a subtle sweetness that echoes the roasted celeriac.
• Fresh parsley: A brightness that cuts through the richness and keeps the final bite from feeling too heavy.

Instructions

Roast the celeriac until it caramelizes:

Preheat your oven to 200°C (400°F) and spread the diced celeriac on a baking sheet with a drizzle of olive oil, tossing to coat evenly. Roast for 25-30 minutes, stirring once halfway through, until the edges turn golden and the flesh becomes completely tender—you'll smell something sweet and almost toasted when it's ready.

Build the flavor base:

While the celeriac roasts, heat olive oil in a large pot over medium heat and add your diced onion and minced garlic, letting them soften for 3-4 minutes until they're fragrant and beginning to turn translucent. You're not looking for color here, just for them to release their sweetness into the oil.

Simmer everything together:

Add the roasted celeriac and diced potato to the pot, then pour in the vegetable broth and bring to a boil before reducing heat to a gentle simmer. Cook for 15-20 minutes until both vegetables are very soft and break apart easily when you press them with a wooden spoon.

Toast the hazelnuts while you wait:

In a small skillet, melt the butter over medium heat and add your roughly chopped hazelnuts, toasting them for 2-3 minutes while stirring occasionally until golden and fragrant. Stir in the finely chopped parsley and a pinch of salt, then set aside to cool slightly—the residual heat keeps them crunchy.

Blend until silky smooth:

Using an immersion blender, puree the soup directly in the pot until completely smooth and velvety, or carefully transfer to a stand blender in batches if that's what you have. This step transforms it from vegetable soup into something that feels almost luxurious.

Finish with cream and seasoning:

Stir in the cream (if using), ground nutmeg, salt, and pepper to taste, then gently reheat if needed—you want it warm but not boiling, which would dull the delicate flavors you've built. Taste as you go; you might find you need less salt than you think.

Serve with crunch on top:

Ladle the soup into bowls and sprinkle generously with the hazelnut crumble just before serving, so it stays crispy rather than softening into the warmth. The contrast between the velvety soup and crunchy topping is where the magic really happens.

Save

There's a moment that happens every time I make this soup when someone tastes it and their face softens, and they say something like, 'What is this?' with genuine surprise—that's the moment I remember why I love cooking. It's proof that simple ingredients, treated with a little care, become something that feels anything but simple.

Why Roasting Changes Everything

Most people think of celeriac as a supporting player, something you chop into a mirepoix and forget about. But roasting transforms it into the star—the dry heat concentrates its natural sugars and creates a subtle caramelization that adds depth you can't achieve by boiling. The first time I noticed this difference was when I got lazy one evening and skipped the roasting step, thinking the result would be close enough. It wasn't—the soup tasted thin and forgettable, like I'd made something out of obligation rather than genuine cooking. That single experience taught me that shortcuts don't always save time; sometimes they just save you from enjoying what you made.

The Hazelnut Crumble as a Game Changer

This crumble started as an afterthought—I had leftover hazelnuts and thought they'd add a nice textural element. What I discovered is that it's actually essential, the part that makes people remember the soup instead of just enjoying it. The toasted hazelnut flavor echoes the roasted celeriac underneath, creating a harmony that feels intentional and complete. It's also the detail that transforms this from a weeknight soup into something you'd serve at a dinner party without apology.

Adaptations That Actually Work

I've made this soup a dozen different ways, and it's flexible enough to bend without breaking. Sometimes I use coconut cream instead of dairy cream, which adds a subtle sweetness that pairs beautifully with the nutmeg. Other times I've added a splash of sherry or a touch of apple juice to brighten the earthiness. What I've learned is that as long as you keep the roasted celeriac as your base and don't skip the hazelnut topping, you can play with proportions and ingredients without losing what makes this soup special.

• For extra richness, drizzle a tiny bit of hazelnut oil into each bowl before serving—it's expensive but a little goes a long way.
• If you can't find good hazelnuts, toasted almonds or even crispy sage leaves work as emergency substitutes for that textural contrast.
• Make a double batch and freeze half without the cream for busy weeks when you want something warming that takes just a few minutes to reheat.

Save

This soup has become my quiet comfort, the dish I make when I want to turn an ordinary evening into something that tastes like care. Serve it hot with crusty bread and watch what happens.

Recipe FAQs

→ Can I make this soup ahead of time?

Yes, the soup keeps well for up to 3 days refrigerated. Prepare the hazelnut crumble fresh before serving to maintain its crunch and optimal texture.

→ What can I substitute for celeriac?

Cauliflower or parsnips work well as alternatives, though they'll provide different flavor profiles. Adjust roasting time based on the vegetable you choose.

→ How do I make this vegan?

Simply replace heavy cream with plant-based cream or coconut milk, and use olive oil instead of butter for the hazelnut crumble. The result is equally delicious.

→ Can I skip roasting the celeriac?

Roasting develops deep caramelized flavors that enhance the soup significantly. For a quicker version, you can simmer directly, but the taste will be less complex.

→ What other nuts work for the crumble?

Walnuts, almonds, or pecans make excellent substitutes for hazelnuts. Toast them similarly until fragrant and golden for the best flavor and crunch.

→ Why add potato to the soup?

Potato adds body and creaminess to the soup while helping achieve that silky smooth texture when blended. It also balances the earthy celeriac flavor beautifully.