It’s not just for lining baking pans. Use it for baking fish en papillote, in which fish, herbs, aromatics and wine are steamed in a paper packet. I’ll also fill a parchment cone with melted chocolate or royal icing to decorate cakes and cookies. Chefs cut out a false lid, or cartouche, sized to fit inside a saucepan. Placed on top of, say, pears in their poaching liquid, the parchment disk keeps them submerged and traps steam. —Trung Vu, chef-instructor at the Institute of Culinary Education’s New York City campus