Pat the chicken breasts dry and season generously with salt, pepper, onion powder, and garlic powder.
Heat olive oil in a skillet over medium-high heat. Sear chicken breasts for 3-4 minutes per side until golden brown but not fully cooked through. Remove and set aside.
In a mixing bowl, combine softened cream cheese, sour cream, minced garlic, chopped spinach, chopped artichoke hearts, half of the mozzarella, and all Parmesan cheese. Stir until smooth. Adjust salt and pepper to taste.
Place seared chicken breasts evenly in the baking dish. Spoon the creamy spinach and artichoke mixture over each piece, covering tops and sides. Sprinkle remaining mozzarella cheese on top.
Preheat oven to 375°F (190°C). Bake uncovered for 25-30 minutes until chicken reaches 165°F internally and topping is bubbly and golden. Optionally broil 2-3 minutes for a crispier top.
Let the dish rest for 5 minutes before serving to allow juices to redistribute and sauce to thicken. Serve hot with your favorite sides.