How to Make It
Build a wood fire in a fire ring (see "Learn to Cook Over Live Fire," below) and let it burn down to low flames and embers (1 to 1 1/2 hours).
Cut foil into twelve 1-ft. squares. Divide into 6 stacks of 2 sheets each and set an apple half on each, cored side up. In a bowl, mix flour, butter, oats, brown sugar, and cardamom with your fingers until evenly moistened with no chunks of butter. Mound an equal amount of topping in each apple cavity.
For each packet, neatly fold one stacked set of corners over an apple half, followed by the opposite set of corners; roll remaining corners snug to fruit to seal.
Using long grilling tongs, move logs from center of fire into a frame to create a flat bed of embers in the center big enough for packets. Remove any flaming wood chunks from ember bed. Set packets, topping side up, on embers. Cook 15 minutes, turning packets over every 5 minutes with grilling tongs and moving positions in ember bed for even cooking. Transfer a packet to a plate and carefully open to check for scorching; if you see any, adjust fire or positions of packets. Cook packets topping side down without turning until topping is lightly browned, 10 to 15 more minutes.
Open packets and let cool a few minutes. In a bowl, whisk whipping cream, crème fraîche, and granulated sugar until thick. Serve with apples.
Learn to Cook over Live Fire
When you're cooking anything more advanced than s'mores, you need a campfire that will work with you. Our favorite design is a log cabin-style arrangement surrounding a tipi of kindling. In a fire ring, stack four large logs in a box shape (use six if you're planning a long cooking time). Add tinder inside the box and arrange kindling in a tipi over it. Light tinder with matches or a lighter in a couple of spots; when it starts smoking, blow gently until flames emerge. It takes 1 to 1 1/2 hours for a campfire to burn down to low flames and embers, the ideal stage for cooking. At that point, spread the fire evenly under the cooking grate, using grilling tongs. Move logs or add more of them as needed.
Camp Sunset, a Modern Camper's Guide to the Great Outdoors (Oxmoor House; May 2016)