Preheat your oven to 425 degrees F. Line a baking tray with foil and lightly spray it with nonstick cooking spray. This ensures the cauliflower won't stick while roasting, allowing for that beautiful caramelization.
Add the chopped cauliflower to the prepared baking tray. Drizzle with olive oil and sprinkle with the yellow curry powder, salt, and pepper. Toss everything until the cauliflower is evenly coated in the oil and seasonings. Spread it out in a single layer to ensure even roasting.
Roast the cauliflower at 425 degrees F for 25 to 30 minutes, or until it starts to char around the edges. This roasting step is essential as it brings out the natural sweetness of the cauliflower. You can use this time to chop the onion, fennel, and celery!
After the cauliflower has been roasting for about 10 to 15 minutes, melt the butter with olive oil in a large Dutch oven or soup pot over medium-low heat. Add the chopped onions, fennel, and celery. Cook until translucent and tender, stirring often, which should take about 10 to 15 minutes. This step is vital as it creates a flavorful base for your soup.
Increase the heat to medium-high and add the minced garlic. Sauté for 30 seconds until fragrant. Next, sprinkle in the flour and cook for an additional 2 minutes, stirring constantly to avoid any lumps.
Reduce the heat to low and pour in the chicken broth along with all the roasted cauliflower except for about ½ cup reserved for garnish. Add in your dried herbs and remaining spices. Bring the mixture to a boil, then reduce it to a simmer for about 5 minutes, allowing all the flavors to meld.
Next, puree the soup using an immersion blender directly in the pot. If you don’t have one, carefully transfer batches to a standard blender but be cautious—leave a corner open for steam to escape to avoid any explosions! A smooth, creamy texture is what you’re aiming for.
If necessary, stir in a little milk or half and half to reach your desired consistency. Taste your delicious soup and adjust with additional salt and pepper if needed. Remember, the seasoning is critical to balancing all those flavors.
Finally, ladle the soup into bowls and garnish with the reserved roasted cauliflower. You can also top it with freshly chopped parsley and roasted pepitas for added texture and flavor.
