Preheat your oven to 400°F (200°C). Spread peeled and chopped kohlrabi and parsnips, along with whole garlic cloves, onto a baking sheet. Drizzle with olive oil and toss to coat evenly. Roast for about 25-30 minutes until vegetables are tender and slightly caramelized, filling the kitchen with a warm, nutty aroma.
While the vegetables are roasting, heat a tablespoon of olive oil in a large pot over medium heat. Add some of the peeled garlic cloves (from the roasted batch) and cook for about 1 minute until fragrant, stirring constantly.
Once fragrant, add the remaining roasted vegetables to the pot. Sauté for 2-3 minutes, stirring gently, to help release their flavors.
Pour in the vegetable broth, bringing the mixture to a gentle simmer. Cook for about 10 minutes to allow the flavors to meld and the vegetables to soften further.
Use an immersion blender to blend the soup until smooth and creamy, or transfer carefully in batches to a regular blender, then return to the pot.
Season the soup with salt and pepper to taste, adjusting the seasoning until it’s just right. Let it simmer for another 2-3 minutes to unify the flavors.
Serve the soup hot, garnished with a drizzle of olive oil or a sprinkle of fresh herbs if desired. The final dish will be thick, silky, and vividly colorful, perfect for a cozy fall meal.
