Prep your oven and pan: Preheat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with olive oil or butter.
Cook the bacon: In a skillet, cook the bacon until crisp.
Drain on paper towels and crumble. Reserve about 1 tablespoon of bacon fat if you want extra flavor in the sauce.
Par-cook the veggies: Lightly steam the broccoli florets until just tender-crisp (about 3–4 minutes) and drain well. If using cauliflower rice, pre-cook and squeeze out excess moisture. Dry veggies prevent a watery casserole.
Make the ranch cream sauce: In a saucepan over medium heat, whisk together heavy cream, cream cheese, mayonnaise, ranch seasoning, garlic powder, onion powder, and smoked paprika.
Stir until smooth and slightly thickened, 3–5 minutes. Season with salt and pepper.
Assemble the base: In a large bowl, combine the chicken, broccoli, cauliflower rice (if using), half the bacon, and half the mozzarella and cheddar. Pour in the ranch cream sauce and stir until everything is well coated.
Transfer and top: Spread the mixture evenly into the prepared baking dish.
Sprinkle the remaining mozzarella, cheddar, and bacon over the top.
Bake: Bake uncovered for 18–22 minutes, until the cheese is melted and bubbly and the edges are lightly golden.
Finish and rest: Let the casserole rest for 5–10 minutes to set. Garnish with chopped parsley or chives before slicing.
Portion for meal prep: Divide into 4–6 airtight containers for easy grab-and-go lunches or dinners.