Preheat and prep: Heat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with olive oil or butter.

Par-cook the vegetables: Toss the broccoli and cauliflower with 1 tbsp olive oil, salt, and pepper. Spread on a sheet pan and roast for 10–12 minutes until just tender. This keeps the casserole from getting watery.

Sauté aromatics: In a skillet over medium heat, warm the remaining 1 tbsp olive oil. Add the red onion and cook 3–4 minutes until softened. Stir in the minced garlic and cook 30 seconds until fragrant.

Make the creamy base: In a large bowl, whisk together sour cream, cream cheese, and heavy cream until smooth. Add paprika, thyme, garlic powder, red pepper flakes (if using), 1 cup cheddar, and the Parmesan. Season with salt and pepper.

Combine: Add the cooked chicken, roasted broccoli and cauliflower, sautéed onions and garlic, and the chopped zucchini to the bowl. Stir until everything is evenly coated.

Assemble: Transfer the mixture to the prepared baking dish. Spread in an even layer. Sprinkle the remaining 1/2 cup cheddar on top. If using, scatter crushed pork rinds or almond flour over the cheese for a crunchy finish.

Bake: Bake for 20–25 minutes, until the casserole is bubbling around the edges and the top is golden.

Rest and serve: Let it sit for 5–10 minutes before serving so it sets slightly. Taste and adjust salt and pepper if needed.