01 - Preheat oven to 400°F.
02 - Wrap beets individually in foil. Slice the top off the head of garlic, drizzle with a little olive oil, wrap in foil.
03 - Place beets, garlic, and quartered onion on a baking sheet. Drizzle onions with 1 tbsp olive oil. Roast for 40–45 minutes, until beets are fork-tender and garlic is soft. Allow to cool slightly.
04 - Meanwhile, heat 1 tbsp olive oil in a large pot over medium heat. Add carrots, potato, and celery; sauté for 6–8 minutes until softened.
05 - Unwrap roasted beets and garlic. Peel beets and roughly chop. Squeeze roasted garlic cloves from skins.
06 - Add roasted beets, garlic, onions, sautéed vegetables, vegetable broth, and water to the pot. Season with salt, pepper, thyme, and cumin. Bring to a boil, reduce heat, and simmer for 10–15 minutes.
07 - Use an immersion blender (or transfer in batches to a blender) to blend soup until smooth and creamy.
08 - Stir in heavy cream. Taste and adjust seasoning. Warm through gently, then ladle into bowls. Garnish with fresh dill or chives.