Preheat your oven to 375°F (190°C).
Lightly grease a 9x13-inch baking dish with butter or cooking spray.
Steam the broccoli and cauliflower for 3 to 4 minutes until they're slightly tender.
Drain well to remove excess moisture.
Mix until smooth.
Add the chicken, broccoli, and cauliflower to the Alfredo mixture.
Stir until everything is evenly coated.
Transfer the mixture to the prepared baking dish.
Top with the mozzarella cheese and remaining Parmesan cheese.
Cover loosely with aluminum foil and bake for 20 minutes.
Remove the foil and bake for another 10 to 15 minutes, or until the cheese is melted, bubbly, and lightly golden.
Let the casserole rest for 5 to 10 minutes before serving.
Sprinkle with chopped parsley and enjoy while warm.