1️⃣ Preheat the oven:
Preheat your oven to 400°F (200°C). Lightly grease a 9×13-inch baking dish with butter or cooking spray. Set it aside.

2️⃣ Prepare the chicken:
Cut the chicken breasts horizontally to create four thin cutlets. Use a rolling pin or meat mallet to pound the thicker parts to even thickness for uniform cooking.

3️⃣ Marinate the chicken:
In a large bowl, whisk together 1 tablespoon of olive oil, minced garlic, Italian seasoning, salt, and pepper. Add the chicken and toss to coat. Cover and refrigerate for 15-30 minutes to allow the flavors to meld.

4️⃣ Cook the spinach:
Heat the remaining 1 tablespoon of olive oil in a large skillet over medium heat. Add the fresh spinach and cook, stirring frequently, until wilted (about 2-3 minutes). Remove from the skillet and set aside.

5️⃣ Prepare the spinach mixture:
In a medium bowl, beat the softened cream cheese until smooth. Stir in the wilted spinach, ½ cup mozzarella cheese, and Parmesan cheese (if using). Mix until well combined.

6️⃣ Assemble the casserole:
Remove the chicken from the marinade, letting any excess drip off. Optionally, sear the chicken in a hot skillet for 1-2 minutes per side to enhance flavor. Arrange the chicken in a single layer in the prepared baking dish.

7️⃣ Top the chicken:
Spread the spinach and cream cheese mixture evenly over the chicken cutlets. Sprinkle the remaining ½ cup mozzarella cheese on top for a melty, golden finish.

8️⃣ Bake:
Place the casserole in the preheated oven and bake for 20-30 minutes, or until the chicken is fully cooked (internal temperature of 165°F) and the cheese is melted and lightly browned.

9️⃣ Serve:
Allow the casserole to rest for 5 minutes before serving. Pair with your favorite side dishes, such as rice, pasta, or a crisp green salad.