Chop the heads off the cauliflower and steam until soft.
Once soft drain and return to saucepan. Using a firm spatula or wooden spoon, stir firmly through the cauliflower heads to break them up. You don't want them mashed but you want small pieces.
Add cream cheese, cheese and cream and stir until incorporated. Add mustard, garlic powder, and salt pepper to taste.
Add mixture to a baking dish, cover with remaining 1/2 c. cheese and broil until bubbly. Even my husband who loathes cauliflower loved this!