Medium heat, 350-400*. Watch them closely as they cook in a matter of just a few minutes.Maybe 7-9 minutes total, something like that. You'll see the edges turning white. That tells you that side is done. Flip and in just a few minutes they'll be ready unless they are unusually thick breasts. They might be too thin to temp. Cut one in the center to check for done just to make sure, but don't overcook which is easy to do with these breasts. If still a little too pink, put back on briefly