- Preheat oven to 375°F. Spray a 9x13 baking dish with non-stick spray, and set aside. 
- Use a sharp knife or kitchen shears to (butterfly) cut the chicken breast horizontally almost in half. Set chicken aside. 
- Mix all of the seasoning ingredients together. Sprinkle the seasoning over both the insides and outsides of the chicken breasts. 
- In a medium bowl, combine softened cream cheese, mayonnaise, parmesan, mozzarella, garlic, and chopped spinach. 
- Divide the spinach stuffing into four equal parts and spoon it into the chicken centers. Using toothpicks, secure the stuffing inside. 
- Place the chicken breasts in a prepared baking dish. Bake, uncovered, for 30-40 minutes, depending on how large your chicken breasts are.  Use a meat thermometer to insure chicken is cooked through to 165°.