Place a mixing bowl in the freezer to chill for about 15 minutes. In the chilled mixing bowl, combine heavy cream and chocolate syrup and whisk them together until peaks form.
Cover the bottom of a 9″ x 13″ baking pan with a flat layer of whole graham crackers. You may need to break off sections of a few graham crackers to match the size of the pan.
Cover the graham cracker layer with about a half an inch of chocolate whipped cream.
Place another flat layer of graham crackers over the whipped cream. Cover this layer with the rest of the whipped cream.
Cover the pan with plastic wrap and place it into the refrigerator overnight to allow the graham crackers to soften and expand. Slice and serve.