Step 1

Cut 2 small triangles from the top corners of a rectangular graham cracker using sharp kitchen scissors. Cut 2 long, thin triangles from the bottom of the graham cracker to create a coffin shape. Repeat with remaining graham crackers using the first one as a template.

Step 2

Lay 6 graham crackers on a plate. Draw crosses and the letters "RIP" on the center of each coffin lid using the black decorating gel.

Step 3

Break 3 dark chocolate squares in half. Leave remaining 12 squares whole.

Step 4

Lay remaining 6 graham crackers on a baking sheet. Place 2 1/2 squares of chocolate on each, leaving room on for the skull. Arrange 11 miniature marshmallows on top of the chocolate in the shape of a skeleton: 4 for arms, 5 for the body, and 2 for legs.

Step 5

Set oven rack about 6 inches from the heat source and preheat the oven's broiler on the low setting.

Step 6

Place graham cracker coffins under the broiler until marshmallows bring to color, 10 to 20 seconds.

Step 7

Place skull candies above the marshmallow skeletons. Drizzle red icing over the s'mores. Sandwich the s'mores with the decorated graham cracker coffin lids.