Preheat oven to 425°F. Place the cut cauliflower and cubed sweet potato on a baking sheet, and drizzle with olive oil and toss to coat well. Season with salt and pepper. Bake for 20-30 minutes, until tender.
Meanwhile, prepare the vegetables and infused herb olive oil. In a sauce pot, combine the sprigs of rosemary and thyme with the olive oil. Over low-medium heat, simmer for about 3-5 minutes. Make sure it's not over heating, as the herbs will burn. Remove from heat and set aside.
In a Dutch oven or cast iron pot, add 2 tablespoons of olive oil to the pot, and sauté the onions for about 3 minutes, then add celery, and cook for another 2 minutes. Add in the garlic and cook for another minute until the garlic releases it's aroma. Stir in the spices, paprika and cumin, simmer for a minute. Add the roasted cauliflower (leaving a few florets for garnishing) and sweet potatoes, combining with the spices. and garlic and combine well. Then add vegetable broth and bring to a boil, then reduce the heat and simmer for about 5 minutes.
Transfer in batches to food processor/blender or use a hand emulsifier and puree until smooth. Add the milk and thyme, simmer until heated through. Then add salt and pepper, and adjust seasoning if needed. Serve hot.
Garnish each bowl with toasted baguettes croutons, thyme, a few cauliflower florets, freshly ground pepper and swirl the infused herb oil. Place any leftover infused herb oil into a sealed container at room temperature for up to a week.
