I am somehow cursed with baking pans that warp. I try to buy the heaviest I can find, and yet.... i invariably hear that horrible "BANG" in the oven when the jelly roll pan twists and warps in the middle of baking. Can anyone recommend a good brand? i have some of those cookie sheets which are insulated (double thick, with air in between) and have never really liked them because the cookies sometimes don't bake on the bottom. However, they don't warp! I saw the gold pans at williams sonoma and wondered if they were as good as they look cause they're pretty, but also, the manufacturer claims they are very nonstick and heaviest metal available for retail. thoughts?