Preheat the oven to 400°F. Spray a 9x13-inch baking dish with non-stick cooking spray. Set aside.
Microwave your cauliflower rice and broccoli according to package instructions. Once cooked, add to a large mixing bowl. To the bowl mix in mushrooms, eggs whites, 1 cup mozzarella cheese, 1 cup parmesan,garlic powder, onion powder, Italian seasoning, butter, and salt. Stir with a rubber spatula until fully combined.
Place the cooked and chopped chicken in your casserole dish in an even layer, covering the bottom.
Layer the cauliflower rice mixture on top of the chicken and top with the remaining 1/2 cup mozzarella and 1/2 cup parmesan.
Cover the dish with foil and bake covered for 25 minutes, remove foil cover and bake another 20 minutes or until the cheese on top has fully melted and started to brown slightly. Let cool for 10 minutes before serving.