solly, you need to make sure you are cutting the potatoes the same exact shape/thickness... also maybe bring your oven temp down a little, toss them every 5-10 minutes. An oven doesn't cook very evenly, let me guess, all the potatoes around the edged were burned, right?
To even out oven temps, its a good idea to keep a pizza stone in the oven. It will keep the oven at a more constant temp, rather than most ovens that have a 20ish degree give or take fluctuation during cooking.
Oh and next time you are near a williams sonoma or what not... pick up some hickory smoked salt and put that on there... lol mmmmm you'll love it
EDIT: Try cooking them on a baking rack instead of a cookie sheet, which I am assuming you are using.
Last edited by JJR4884; 07-26-2011 at 12:15 PM.