I got so tired of buying one kind of baking sheet after another, only to have them scratch, stick or rust quickly. On a shopping trip one summer, I bought a few extra large cookie sheets, and knew right away that I had found a cookie sheet that would last. Nordic Ware is designed for commercial use. They’re aluminum for even baking, with a 1″ rim.
The big sheet pan, Nordic Ware Naturals Big Sheet Baking Pan, is 21″ X 15″ which is about the biggest that will fit most standard ovens. If you use sheets that fill your oven, its best not to use three at a time in convection mode, because the space for circulation at the edges simply isn’t there. Just be aware of how much space is available at the edges. I find it easy enough to bake one of these jumbo sheets of cookies while preparing the next sheet.
The only draw back to these baking sheets is that they aren’t dishwasher proof, but the jumbo ones are too big for the dishwasher in any event. I hate washing dishes, but these wash so easily in any size that it isn’t really a problem for me. Later I bought three standard size, Nordic Ware Bakers Half Sheet, 13 by 18 by 1 inch, and put one of them in the dishwasher just to try it, and it did take the finish off, but actually its still a much better baking sheet than any I had before. You can get them in a variety of other sizes, but these are the two sizes I use over and over again.