Celeriac Soup with Hazelnut Crumble

There's something magical about the moment you first roast celeriac and realize it's nothing like the raw, slightly sulfurous root you'd dismissed before. A friend handed me a wooden spoon one autumn afternoon and insisted I taste the soup she'd made, and I watched the steam rise while she explained how the roasting transforms everything into something almost sweet. That spoonful changed my mind about an entire vegetable I thought I'd never love.

I made this for my partner on a cold Wednesday night when the market had just received fresh celeriac, and watching them try it for the first time reminded me why I love cooking. They kept going back for more, saying the earthiness felt grounding, and suddenly this humble root vegetable had sparked a whole conversation about forgotten flavors we should cook with more often.

Ingredients

• Celeriac (700 g), peeled and cubed: This is your star, and roasting it unlocks a warmth and depth that steaming never achieves; peel generously to remove the knobby bits and any dark spots.
• Onion and garlic: The foundation that adds sweetness and body to balance the earthiness; don't skip the sautéing step, as it mellows the raw bite.
• Potato (150 g), peeled and diced: Acts as a natural thickener and adds creaminess without requiring cream, though cream is lovely if you want it.
• Vegetable broth (900 ml): Choose a good quality one you'd actually drink on its own, as it's the second major flavor player here.
• Olive oil (2 tbsp total): Split between roasting and sautéing for maximum flavor development in two different ways.
• Heavy cream or plant-based alternative (100 ml): Optional but it does add a silky finish; you can absolutely skip it if you prefer the soup lighter.
• Ground white pepper (1/2 tsp): Milder than black pepper and won't speckle your pale, elegant soup; it lets the celeriac shine.
• Hazelnuts (70 g), roughly chopped: Toast them yourself rather than using pre-roasted for that fresh, bright nuttiness that anchors the whole dish.
• Butter and sea salt for the crumble: The butter coats and crisps the hazelnuts, while salt awakens their natural sweetness.
• Fresh parsley (1 tbsp), finely chopped: A finishing touch that adds color and a whisper of freshness.

Instructions

Heat your oven and prepare the celeriac:

Set your oven to 200°C (390°F). Toss the cubed celeriac with 1 tablespoon of olive oil, a pinch of salt, and white pepper until evenly coated. Spread it on a baking tray in a single layer so the pieces can roast rather than steam, which is how you get that golden, caramelized edge.

Roast until golden and tender:

Roast for 25 to 30 minutes, stirring halfway through so nothing sticks or browns unevenly. You'll smell when it's done—that warm, toasted aroma is your signal that the celeriac is soft inside and deepening in color outside.

Build your flavor base while the oven works:

Heat the remaining 1 tablespoon of olive oil in a large pot over medium heat and add your chopped onion. Sauté for about 4 minutes until it turns translucent and soft, then add the minced garlic and diced potato. Cook for another 2 minutes until everything starts to smell incredible.

Combine and simmer gently:

Add the roasted celeriac to the pot along with your vegetable broth, then bring everything to a gentle boil before reducing the heat to a simmer. Let it bubble quietly for 15 to 20 minutes until all the vegetables are completely soft and break apart easily with a wooden spoon.

Toast the hazelnuts for crunch:

While the soup simmers, place your chopped hazelnuts in a dry skillet over medium heat and let them toast for 3 to 4 minutes, stirring often so they color evenly without burning. You'll hear them start to crackle slightly, and the kitchen will smell like a forest floor in the best way possible.

Coat the nuts with butter and salt:

Add butter and sea salt to the warm hazelnuts, stirring constantly until they're golden, glossy, and fully coated. Transfer them to a small bowl to cool slightly so they stay crispy.

Blend until silky smooth:

Using an immersion blender, purée the soup directly in the pot until it's completely smooth and velvety, or work in batches with a countertop blender if that's what you have. Stir in the cream if you're using it, then taste and adjust the seasoning with more salt and white pepper.

Finish and serve:

Ladle the soup into warm bowls and top each one generously with the cooled hazelnut crumble and a small handful of fresh parsley. The contrast between the warm, creamy soup and the cool, crisp topping is where the magic happens.

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My grandmother once told me that a good soup is like a good conversation—it needs patience, good ingredients, and something unexpected at the end. This celeriac soup with its crispy hazelnut topper finally showed me what she meant, turning a simple November evening into something memorable.

The Magic of Roasting Root Vegetables

Roasting changes chemistry in ways that boiling never can; the heat caramelizes the natural sugars in the celeriac and creates depth that you simply can't achieve by simmering it straight in broth. I learned this the hard way by making the soup the quick way first, and the difference was so clear that I've never skipped this step since. It's worth the extra 30 minutes because you're essentially building flavor in the oven while you prep everything else.

Why This Soup Stays Elegant

The beauty of this soup lies in its restraint—there's no cream masking the celeriac's true character, no heavy spice competing for attention, just clean, earthy flavors allowed to be themselves. The white pepper was a revelation once I understood it doesn't speckle the surface but lets the paleness of the soup become part of its visual appeal. What makes it feel special isn't complexity but rather the confidence to let one vegetable shine.

Customizing Without Losing the Soul

This soup is naturally forgiving, and the notes built into the original recipe point the way toward variations that feel right. A squeeze of fresh lemon at the end brightens everything without overwhelming, while a tiny pinch of fresh thyme adds an herbal note that plays beautifully against the earthiness. If you're vegan, the soup tastes just as luxurious without cream, and the hazelnut crumble actually becomes more essential as your textural anchor.

• A splash of dry white wine stirred in before the cream adds sophistication and a subtle complexity that lingers.
• Crispy sage leaves on top instead of (or alongside) parsley change the flavor direction to something more autumn-forward.
• A drizzle of truffle oil over the crumble transforms this from weeknight dinner into something worthy of a special occasion.

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This is the kind of soup that makes you fall in love with vegetables all over again, one spoonful at a time. Make it once for yourself and it'll become a quiet favorite you return to whenever the seasons turn cold and you want something that tastes like comfort and care.

Common Questions

→ What does celeriac taste like?

Celeriac has a mild, earthy flavor reminiscent of celery and parsley with subtle sweet undertones. When roasted, it develops a deeper, nuttier profile that pairs beautifully with creamy preparations.

→ Can I make this soup ahead of time?

Absolutely. The base soup reheats beautifully and can be stored in the refrigerator for up to 3 days. Prepare the hazelnut crumble fresh just before serving to maintain its crisp texture.

→ Is this soup suitable for freezing?

Yes, freeze the soup base without cream for up to 3 months. Thaw overnight in the refrigerator, reheat gently, and stir in cream when warming through. The hazelnut crumble is best made fresh.

→ What can I substitute for hazelnuts?

Walnuts, pecans, or toasted pumpkin seeds work wonderfully as alternatives. Each brings its own distinct flavor profile while maintaining that essential crunchy contrast to the smooth soup.

→ How do I achieve the smoothest texture?

Roasting the celeriac first softens it completely before blending. Using an immersion blender or high-speed countertop blender ensures a silky, lump-free consistency. Adding cream creates extra velvety richness.