1Heat broiler to high and place oven rack in middle level of oven. Top each graham cracker with a 3-inch square of bittersweet chocolate and one marshmallow.
2Place assembled s’mores on a baking sheet and place under the heated broiler (in the middle of the oven, not at the top, where they will burn quickly). Watch them very closely and remove once the marshmallow is well browned. Serve.