The French call it "en papillote," the Italians "al cartoccio," but we Americans simply call it cooking in parchment. This cooking method actually involves wrapping a parcel of food, typically fish or chicken with vegetables, in parchment paper. It's then baked in the oven until the parchment puffs and it's all cooked through.
Not only is this technique easy to do, it also looks quite impressive at the dinner table (there's a big reveal when everyone cuts open their own packet) and it's very healthy. You barely need any oil or fat to cook in parchment because the food effectively steams inside the parchment. What you're left with is very tender meat and vegetables, flavored with whatever herbs, spices or sauces you've included.