1. Preheat your oven to 400°F (200°C) and lightly grease a 9×13-inch baking dish.

2. Cut each chicken breast in half horizontally to create four thin cutlets. Pound the thicker ends to ensure even thickness.

3. In a bowl, whisk together 1 tablespoon of olive oil, garlic, Italian seasoning, salt, and black pepper. Toss the chicken in the marinade, cover, and refrigerate for 15–30 minutes.

4. In a skillet, heat the remaining olive oil over medium heat. Add spinach and cook for 2–3 minutes until wilted. Set aside.

5. Beat softened cream cheese in a bowl, then stir in spinach and ½ cup mozzarella cheese (and Parmesan if using).

6. Optionally, sear the marinated chicken in a hot skillet for 1–2 minutes per side for added flavor.

7. Arrange the chicken in the baking dish, spread the cream cheese and spinach mixture over it, and top with remaining mozzarella.

8. Bake for 20–30 minutes until the chicken reaches an internal temperature of 165°F (75°C) and the cheese is melted and lightly browned.

9. Let the casserole rest for 5 minutes before serving.