Preheat oven to 400 degrees. Roast cauliflower coated with olive oil, 1 tsp. garam masala, 1/2 tsp. curry powder, 1/2 tsp. turmeric, and salt and pepper for 25 minutes--stirring once or twice at 15 and 20 minutes.
While cauliflower is roasting, melt coconut oil on medium heat.
Add onions and cook for 5 minutes.
Add garlic and cook for 1 minute.
Add carrot and celery and cook for an additional 5-10 minutes until soft.
Add remaining spices, stir, and cook for an additional minute.
Add broth to deglaze pan, then add coconut milk.
When cauliflower is done roasting, add to pan and simmer for 5 minutes.
Using an immersion blender, blend to desired consistency (you can also use a blender, but be very careful when blending hot liquids).