Preheat the oven to 350°F (175°C).
In a large bowl, combine softened cream cheese, sour cream, mayonnaise, garlic powder, and dried minced onion; mix until smooth.
Fold in the cooked chicken, thawed spinach (if using), grated parmesan, and half of the chopped bacon. Mix well to coat everything in the creamy sauce.
Spread the mixture in a greased 9x13 baking dish.
Sprinkle the mozzarella and remaining bacon evenly over the top.
Bake for 35 minutes, until hot and bubbly with a slightly golden top.
Let sit for 5 minutes before serving. Best with a simple side salad or fresh greens!