Prepare the Oven and Baking Dish: Preheat your oven to 375°F. Lightly grease a 9×13-inch baking dish.

Season the Chicken: Pat the chicken breasts dry with paper towels. Season both sides with ½ teaspoon of salt and ¼ teaspoon of black pepper. Place the chicken breasts in the prepared baking dish.

Make the Spinach Artichoke Mixture: In a medium bowl, combine the sour cream, softened cream cheese, grated Parmesan cheese, onion powder, garlic powder, the remaining ½ teaspoon of salt, and ¼ teaspoon of black pepper. Mix until smooth and well combined.

Add Spinach and Artichokes: Fold the thawed and drained spinach and chopped artichoke hearts into the sour cream mixture until evenly distributed.

Assemble the Casserole: Evenly spread the spinach artichoke mixture over the chicken breasts in the baking dish, ensuring each piece is well covered.

Top with Mozzarella: Sprinkle the shredded mozzarella cheese evenly over the top of the spinach artichoke layer.

Bake: Place the baking dish in the preheated oven and bake for 30-35 minutes, or until the chicken is cooked through (internal temperature of 165°F) and the cheese is melted and bubbly.

Serve: Remove from the oven and let it rest for a few minutes before serving. Enjoy this creamy casserole on its own or with a side of rice or pasta for a complete meal.