This recipe fits perfectly in an 8x11-inch pan. That makes the candy bark between 1/4- and 1/2-inch thick (depending on if you're measuring just the melted chocolate or if you are measuring the cookie pieces as well). A bark of that thickness can sit out at room temperature without melting. Anything thinner will start to melt at room temperature and needs to be kept in the fridge. So if you want, you can use a larger pan and make this Oreo candy bark thinner, but we wouldn't recommend it.