Steps
1. Preheat oven to 375°F (190°C).
2. In a small bowl, mix cream cheese, mozzarella, Parmesan, chopped spinach, and minced garlic until well combined.
3. Carefully slice the chicken breast horizontally to create a pocket, without cutting all the way through.
4. Stuff the cheese and spinach mixture into the chicken pocket. Secure with toothpicks if necessary.
5. Rub the outside of the chicken breast with olive oil, salt, and pepper.
6. Place the chicken in a baking dish and bake for 25-30 minutes, or until the chicken is cooked through and juices run clear.
7. Remove toothpicks before serving. Let rest for 5 minutes, then enjoy.