Place the brie on a large piece of heavy-duty foil and poke holes in the top with a knife. Drizzle with the maple syrup and then sprinkle with the thyme leaves, cinnamon and cayenne. Wrap the foil around the wheel, sealing it at the top.
Place the foil pack near the edge of your campfire (not over a direct flame) and warm until heated through, 5 to 7 minutes, rotating with tongs to ensure even heating. Remove to a plate and carefully peel back the foil.
Serve the brie with bread or crackers and sliced apple or pears.
Alternatively, heat the foil-wrapped brie in a preheated 400-degree oven for 10 to 15 minutes.