How long to cook stuffed chicken breasts

Ochef.com answered this question. Here are some quotes from the webpage.

According to the USDA:

Round chicken/turkey: 165°F / 74°C
Whole chicken/turkey: 180°F / 82°C
Poultry breasts, roasts: 170°F / 77°C

Additionally, the USDA says the thighs and wings of poultry should be cooked "until the juices run clear."

Although the following temperatures will make the meat safe to eat, you might want to drop the temperature by 3-5°C for more flavor.

One thing I wonder is if your oven temperature is accurate? An oven thermometer helps there. As well as a pizza stone to maintain a steady temperature. Also, how big was your chicken? Maybe you didn't cook long enough for the weight.

The method I use is this: Pre-heat the oven to 450. Clean bird, remove innards, truss. Salt (Tbls or so) and pepper or otherwise rub on marinade. Place the bird on a large cast iron skillet and cook for 1 hour. Remove bird and let rest for 10 minutes and meanwhile make a sauce utilizing the remnants in the pan. The skin is brown and the meat is juicy. This method is in Michael Ruhlman's, 'Ratio'. I find it to be a great method for basic roasted chicken.

I usually use a 4 - 5 lb chicken and haven't checked the internal temps since the first few times of using this recipe except for when I'm at or over the upper end.