Preheat oven to 400°F (200°C).
Cut cauliflower in pieces and place on a baking tray.
Bake until cauliflower is browned and soft.
Place 2 tablespoons of olive oil in cooking pot over medium heat.
Add the onion and sauté until soft.
Add cooked cauliflower.
Add chili flakes, salt, turmeric, and cumin.
Add vegetable broth. Bring to a boil, then reduce to a simmer.
Cook until cauliflower is much softer. Add water if necessary.
Remove from heat.
Using an immersion blender, blend all ingredients in the pot. If no immersion blender is available, a standard blender will work just as well.
Serve with toasted croutons if desired.