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

Slice chicken breasts horizontally to create thinner cutlets and set aside.

Combine olive oil, minced garlic, Italian seasoning, salt, and black pepper in a bowl. Marinate the chicken cutlets for 15-30 minutes.

In a skillet over medium heat, add olive oil and sauté fresh spinach for 2-3 minutes until wilted.

In a separate bowl, beat softened cream cheese until smooth, then fold in sautéed spinach and half of the mozzarella cheese.

Optionally, sear marinated chicken in the skillet for about 2 minutes on each side until golden brown.

Arrange chicken cutlets in the baking dish, spoon the cheese and spinach mixture over the chicken, and top with remaining mozzarella.

Bake in the preheated oven for 20-30 minutes until cheese is bubbly and chicken reaches 165°F (74°C).

Let the casserole rest for about 5 minutes before serving.