Prep the oven and pan. Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with butter or olive oil.

Cook the cauliflower. If using fresh cauliflower, cut into bite-size florets. Steam or microwave until just tender, about 5–7 minutes. If using frozen, microwave according to package directions. Drain well and pat dry to remove excess moisture.

Make the creamy sauce. In a large skillet over medium heat, melt butter or warm olive oil. Add minced garlic and cook 30–60 seconds until fragrant. Stir in cream cheese, heavy cream, and chicken broth. Whisk until smooth and creamy, about 2–3 minutes.

Season it up. Add onion powder, smoked paprika, salt, and pepper. Stir in 1.5 cups shredded cheddar and 1/2 cup mozzarella (if using) until melted into the sauce.

Combine the base. In a large bowl, mix the cooked cauliflower and shredded chicken. Pour the cheese sauce over the top and toss gently to coat everything evenly.

Assemble the casserole. Transfer the mixture to the prepared baking dish. Sprinkle the remaining cheddar and mozzarella over the top. Add crumbled bacon if you like.

Bake to bubbly. Bake for 18–22 minutes, until the casserole is hot and the cheese is melted and lightly browned around the edges. For extra color, broil for 1–2 minutes at the end, watching closely.

Finish and serve. Let it rest for 5 minutes to set. Garnish with chopped parsley or chives. Serve warm.