Preheat oven to 375°F and grease a 9x13 inch baking dish.
Steam cauliflower florets until just tender, about 8 minutes, then drain very well and pat dry with paper towels.
In a large bowl, mix together cream cheese, sour cream, 1 1/2 cups cheddar cheese, half the bacon, green onions, garlic powder, salt, and pepper until well combined.
Fold in the cauliflower florets until evenly coated, then transfer to the prepared baking dish.
Top with remaining 1/2 cup cheddar cheese and remaining bacon.
Bake for 25-30 minutes until bubbly and golden brown on top.
Let rest for 5 minutes before serving.