Heat the oven to 400°F. Place the chicken into a 2-quart shallow baking dish. Spoon 1 cup sauce over the chicken. Sprinkle with the mozzarella and Parmesan cheeses.
Bake for 15 minutes or until the chicken is hot and the mozzarella cheese is melted.
Heat the remaining sauce in a 2-quart saucepan over medium heat until hot and bubbling, stirring occasionally. Serve the sauce with the chicken and spaghetti.