Preheat the oven to 375˚F. Lightly spray a 9 inch square baking dish and set aside.
Steam the cauliflower until crisp-tender. Remove from heat and set aside.
Meanwhile, in a medium saucepan bring the cream to a simmer. Whisk in the cream cheese and dijon mustard until smooth. Mix in 1 cup of the cheddar cheese until melted and smooth. Mix in the cauliflower and pour the mixture into the prepared baking dish.
Sprinkle the remaining ½ cup of cheese over the cauliflower mixture and bake in the preheated oven for around 15 minutes. Serve immediately.