Boneless turkey breast: Temp and Time?
Regardless of what cooking method and cooking temperature you decide on, your best bet to achieve perfectly cooked, moist, and safe poultry is to use a probe or instant read thermometer to tell you when the breast is done. Otherwise, you'll be guessing, and guessing with poultry breast meat is very, very difficult and most often yields overcooked, dry meat. A thermometer takes the guesswork out of trying to cook such a temperature sensitive food as poultry.
Your target temperature for poultry breast meat should be 150 degrees F. Adjust when you pull it from the oven based on the size, shape, and temperature you're baking it at.
My recommendation is to Roast low and slow on a rack....@ 200-225*
Depending on the weight, or size, of the turkey breast will ultimately determine the length of time needed to cook it thoroughly,... without knowing the specifics, you are looking at 2-3+ hours.
If you would like some opinions of others, have a look here at a similar recent thread.