Season the chicken with garlic powder, salt, and pepper and place in Crock-Pot for 2 hours on high or 4 hours on low.
When the chicken is almost cooked, add the well drained spinach, artichoke hearts, cream cheese, and Parmesan cheese.
Cook for another hour until the cheeses are well and stir to incorporate flavors.
Top with mozzarella cheese and serve.
Notes
If you'd rather bake this in the oven, simply combine all ingredients except the mozzarella cheese and cook it at 375°F for about an hour, adding mozzarella to the top for the last 10 minutes.