Add ¼ cup graham cracker crumbs to each empty jar. Gently tamp down with the back of the spoon.
Warm the dessert topping in microwave until it is pourable, about 1 minute. Top each of the graham cracker layers with 2 Tablespoons of the dessert topping. Gently tap the jars on the counter to help spread out the sauce.
Turn the broiler of the oven on. Top each jar with ¼ cup mini marshmallows. Place the jars on a baking sheet and place under the broiler. Watch closely and remove once the marshmallows begin to melt and are lightly browned. Drizzle with additional sauce if desired and serve warm.