Preheat oven to 400°F.
Mix Mozzarella and Parmesan together in a medium bowl.
In a bowl, mix together the ricotta, half the cheese mixture, spinach, half the garlic, and Italian seasoning until combined.
Oil a 13x9-inch baking dish with olive oil or spray with no stick cooking spray.
Add the chicken breasts in a single layer to the pan.
Season with salt, pepper, and remaining garlic.
Spread the ricotta and spinach mixture over the top of the chicken breasts in an even layer.
Cover completely with the marinara.
Bake for about 20 minutes or until the thickest section of the chicken reaches an internal temperature of 160°F.
Remove from oven, add the remaining cheese mixture and place back in the oven until the cheese is melted.
Remove from oven and allow chicken to rest about 5 to 10 minutes before serving.