Start by preheating your oven to 375°F (190°C). While the oven heats up, you can get everything else ready.
Gently steam your broccoli florets until they’re tender but still a bit crisp. Don’t overdo it—you want the broccoli to hold its shape after baking.
In a large bowl, combine cream cheese, sour cream, heavy cream, garlic powder, onion powder, paprika, mustard (if using), and a pinch of salt and pepper. Stir well until the mixture is smooth and creamy.
Once your creamy base is ready, fold in the cooked chicken and steamed broccoli. Stir everything together so that every bite gets some of that cheesy goodness.
Grease your casserole dish lightly, then pour the mixture in. Use a spatula to spread it out evenly so it bakes uniformly.
Sprinkle shredded cheddar and grated Parmesan cheese generously over the top. This creates a gooey, golden top layer that’s irresistible.
Place the dish in the oven and bake for about 20–25 minutes. You'll know it's ready when it’s bubbling and the cheese on top is a beautiful golden brown.
Let it rest for a few minutes before serving. This helps the casserole firm up and makes it easier to serve.