jelly roll pan [jel-ee rohl pan] noun
Also half-sheet pans and/or rimmed cookie sheet pans. A pan for baking jelly rolls. The typical dimensions of a jelly roll pan will be 12 ½ x 17 ½ x 1-inch deep. There are other versions that vary in size, but most do have the 1-inch depth. The sides enable the cake to rise when baking and prevents overflow.
Jelly roll pans are also handy for catching overflow from juicy pies, baking cookies, or even roasting savory foods. Anytime you need a broad surface for items to bake or roast in a single layer, such as with oven fries, this is the go-to pan.