01 - Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.
02 - On the prepared baking sheet, toss the cubed celery root, carrots, onion, and garlic with 2 tablespoons olive oil, ½ teaspoon salt, and pepper. Spread in a single layer and roast for 25–30 minutes, stirring once halfway through, until vegetables are golden and fork-tender.
03 - Transfer the roasted vegetables to a large pot. Add the drained white beans, vegetable broth, bay leaf, dried thyme, and smoked paprika. Bring to a boil over medium-high heat, then reduce to a simmer and cook for 10 minutes to allow the flavors to meld.
04 - Remove and discard the bay leaf before blending.
05 - Using an immersion blender, puree the soup directly in the pot until smooth and velvety. Alternatively, work in batches using a stand blender, filling no more than halfway and venting the lid.
06 - Stir in the cream and fresh lemon juice. Taste and adjust seasoning with additional salt and pepper as needed.
07 - Warm the soup gently over low heat if needed. Ladle into bowls and garnish with chopped parsley or chives and a light drizzle of olive oil.