Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine the softened cream cheese, sour cream, heavy cream, mayonnaise, minced garlic, a pinch of salt, and a dash of pepper. Stir everything together until smooth and well combined.
Now, add the cooked chicken, thoroughly drained spinach, chopped artichoke hearts, and grated Parmesan cheese to the bowl. Mix well until all ingredients are evenly coated – remember to save the mozzarella cheese for later!
Lightly spray a 9" x 13" baking dish with nonstick spray. Pour the delicious chicken mixture into the dish and spread it out evenly.
Generously sprinkle the reserved shredded mozzarella cheese over the top of the casserole.
Bake for 20 minutes. After 20 minutes, increase the oven temperature to 400°F (200°C) and bake for another 5 minutes, or until the mozzarella is beautifully golden brown and bubbly.
Allow the casserole to cool for a few minutes before serving.