Put the chicken breasts frozen or fresh in an oven safe pan and pour the jar of spaghetti sauce over the chicken.
Let the chicken marinade in the refrigerator at least 4 hours up to overnight if you so desire, or bake the chicken right away.
To bake the chicken, cover the pan with aluminum foil, shiny side down, and bake at 375° for 45-55 minutes, or until the internal temperature of the chicken is at least 165°.
Cook time may vary depending on how thick the breasts are and if you are cooking from frozen or not. In general, no matter what the chicken, it will be done within 75 minutes.Note: While there are 6 chicken breasts used, I argue that is 12 servings due to the size of most chicken breasts! Cut them in half and you are still getting a ton of food!