Preheat oven to 400°F with rack in center position.
Place the cauliflower in a steamer basket over boiling water. Steam until just fork-tender, about 6–7 minutes.
Transfer the cauliflower to a colander and let it drain for a minute or two. Pat very dry with paper towels to remove as much excess moisture as possible.
Add the cauliflower to a large bowl with the cream cheese, heavy cream, butter, garlic powder, and dried dill. Season with salt and pepper and toss gently to combine.
Transfer to oven-safe casserole dish. Top with shredded Italian cheese blend and crumbled bacon.
Bake 8-10 minutes until cheese is melted and nicely browned on top.
Remove from oven and top with fresh chives. Serve immediately.