Preheat oven to 400 degrees. Line a baking sheet with aluminum foil and set aside.

In a bowl combine carrots, cauliflower and onion, then pour olive oil over the vegetables and stir to combine. Pour onto the lined baking sheet and season with salt and pepper. Roast vegetables for 35 minutes, then remove from oven.

Gently scrape contents of the baking sheet into a food processor and pour in the vegetable broth and water. Process until desired consistency (if you like your soup a little more liquidy add more water).

Pour contents of the food processor into a pot and heat until warm. Ladle into bowls and serve (I reserved two cauliflower florets and put them on top for garnish)