Can I use aluminum foil or parchment paper in the oven?

You can use foil or parchment paper as a liner on the baking pan, but it must be cut to the exact size of the pan and not raised above or hanging below the edges. NEVER cover the crumb tray or oven walls with foil or parchment paper. Do not leave the liner on the baking pan during preheating and cooking unless there is food on it to weigh it down and keep it secure.