In a large pot, sweat carrots, onions, celery root, ginger, and garlic in 3 tablespoons butter at very low heat until soft, about 30–45 minutes. Remove vegetables. Add 2 tablespoons butter and the spices. Cook for 5 minutes, gently toasting spices in butter to “bloom” the flavors. Add orange juice and simmer for 5–10 minutes.

Return vegetables to pot. Add water and chicken stock, cover, and simmer for 1/2 hour. Adjust seasoning with salt and white pepper.

Remove bay leaves and cinnamon sticks. Transfer soup in batches to a blender and purée until smooth. Return to pan to heat through. Serve hot.