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

2️⃣ Prepare the chicken: Slice the chicken breasts in half horizontally to create four cutlets. Use a rolling pin or meat mallet to pound the thicker ends to an 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. Toss the chicken in the mixture until evenly coated. Cover and marinate in the fridge for 15-30 minutes.

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

5️⃣ Make the spinach filling: In a medium bowl, beat the softened cream cheese until smooth. Fold in the sautéed spinach, ½ cup of mozzarella cheese, and Parmesan cheese (if using). Stir until well combined.

6️⃣ Assemble the casserole: Arrange the marinated chicken cutlets in a single layer in the prepared baking dish. Spread the spinach and cream cheese mixture evenly over the chicken. Sprinkle the remaining ½ cup of mozzarella cheese on top.

7️⃣ Bake: Place the dish in the preheated oven and bake for 20-30 minutes, or until the chicken is fully cooked (internal temperature of 165°F/74°C) and the cheese is melted and lightly golden.

8️⃣ Rest and serve: Let the casserole rest for 5 minutes before serving to allow the flavors to meld. Serve warm with a side of rice, pasta, or crusty bread.