Preheat oven to 375°F.
Add steamed broccoli to the bottom of a 10x7 casserole dish.
Sprinkle half of the mozzarella and Parmesan over the broccoli.
Layer the cooked chicken evenly on top.
In a bowl, mix together the Alfredo sauce, milk, cottage cheese, and seasonings until smooth and well combined.
Pour the sauce evenly over the casserole, gently poking around so it settles throughout (no need to fully mix).
Top with the remaining mozzarella and Parmesan.
Bake uncovered for 35 minutes, or until hot and bubbly.
Broil for 2–3 minutes until the top is golden and slightly crispy.
