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.