How to Make It
Preheat oven to 425°F. Coat a 13- x 9-inch baking dish with cooking spray. Set aside.
Fit a large pot with a steamer basket, and fill with 1 inch of water. Add cauliflower florets, and cover. Bring to a boil over medium-high. Reduce heat to medium, and steam until cauliflower is very tender, about 20 minutes. Remove from heat, and let stand 5 minutes.
Meanwhile, stir together cream cheese and sour cream in a large bowl until very smooth, about 1 minute. Fold in garlic powder, 1 cup each of the Cheddar and pepper Jack, half of the bacon, and 3 tablespoons of the chives. Fold in warm cauliflower. Spoon into prepared baking dish. Sprinkle with remaining bacon, Cheddar, and pepper Jack.
Bake in preheated oven until cheese is melted and top starts to brown, 15 to 20 minutes. Sprinkle with remaining 1 tablespoon chives. Serve hot.