Crush graham crackers in a zippered plastic bag using a rolling pin. Mix in melted butter and 2 Tablespoons sugar. Line two cupcake tins with cupcake paper liners. Add 2 teaspoons graham cracker mixer to each cupcake liner and flatten with the back of a spoon. (Reserve the extra graham cracker crust for later.)
Bake the graham cracker crusts in the oven for about 5 to 6 minutes. Remove from oven and allow to cool while working with the cupcake batter.
In a large mixing bowl, add canned pumpkin, vegetable oil, eggs, water and vanilla extract and mix together thoroughly with an electric mixer.
Add sugar, cake mix and pudding mix and mix again but be careful not to over mix. Use a rubber spatula to scrape the sides and bottom of the bowl.
Use a large cookie scoop (three tablespoons) to portion batter into the liners on top of the graham cracker crust that's already been baked.
Bake cupcakes for 19 to 20 minutes at 350 degrees F. Once done baking, allow to cool on a baking rack.
Add chocolate squares and shortening to a small microwave safe bowl. Microwave on 50% power in 30 second increments to melt. Mix between increments.
Once cool, spread a little bit of frosting on each cupcake and work on the marshmallows. See below.
Prepping the Marshmallows
Cut marshmallows in half and place on a cookie sheet that's lined with parchment paper with the cut side UP. Broil in your oven for 1 minute (watch closely or they may burn). My oven broils at 550 degrees F and I moved the oven rack the second spot from the top. Broiling them in the oven turned out the best (the best looking marshmallows but if you have a torch, it's actually easier). Remove marshmallows one by one and place three halves on each cupcake.
If you have a kitchen torch, you can torch them! I found that torching the cut side is best. Be careful not to burn your marshmallows although some people like them "burnt" for their s'mores!
Use a spoon to drizzle chocolate over the marshmallows and sprinkle leftover graham cracker crumbs on top.
If you're not going to decorate the cupcakes the same day you make them, be sure to store them in an airtight container overnight.