Place the water and cauliflower in a pot and boil it for ten minutes. Remove the cauliflower with a slotted spoon. Do not discard the water and keep it in the pot.
Add the cauliflower to a food processor or blender. Puree the cauliflower, garlic powder, salt, pepper and milk with one cup of liquid from the pot.
Add the broccoli & shredded carrot to the pot, and add the white sauce from the processor/blender. Bring to a boil, and lower the heat to a simmer for 30 minutes.