Preheat oven to 375°F and lightly grease a 9×13-inch baking dish.
Steam or blanch broccoli until just tender, then drain well.
In a large bowl, mix chicken, broccoli, turkey bacon, garlic, mozzarella, cheddar, and ranch dressing.
Spread mixture evenly in baking dish.
Sprinkle the top with additional cheddar and mozzarella.
Bake for 25–30 minutes until hot and bubbly.
Let rest 5–10 minutes before serving.
