Heat oven to 350 degrees. Place in pan. Add 1 tablespoon butter per breast. Bake for approximately 1 hour turning over at 1 hour. After 1 hour add approximately 1 to 1 1/2 tablespoons per breast Prego Spaghetti Sauce. Bake another 15 minutes. Then add Mozzarella cheese to each breast. When melted it's ready to serve.