Preheat and prep: Heat your oven to 425°F (220°C). Lightly grease a 9x13-inch baking dish.
Roast the cauliflower: Toss the florets with olive oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper.
Spread on a sheet pan and roast for 18–22 minutes, until tender with lightly browned edges. Lower oven to 375°F (190°C).
Cook the bacon: While the cauliflower roasts, cook bacon until crisp. Drain and crumble.
Set aside.
Make the sauce: In a large bowl, beat cream cheese until smooth. Mix in sour cream, heavy cream, ranch seasoning, garlic powder, onion powder, remaining salt and pepper. Stir until creamy with no lumps.
Add cheeses: Fold in 1 cup cheddar and the mozzarella.
The mixture should be thick and spreadable.
Combine with chicken and cauliflower: Add the shredded chicken and roasted cauliflower to the bowl. Gently fold to coat everything in the sauce.
Assemble the bake: Transfer to the prepared baking dish. Smooth the top.
Sprinkle with the remaining 1/2 cup cheddar and half the crumbled bacon.
Bake: Bake at 375°F (190°C) for 18–22 minutes, until bubbly around the edges and cheese is melted and golden.
Finish and garnish: Let it rest for 5–10 minutes to set. Top with the remaining bacon, green onions, and parsley.
Serve: Scoop into bowls and enjoy hot. Pair with a simple salad or steamed green beans for a complete meal.