Gather your supplies. Including what the boxed cake mix calls for (eggs, oil, water, etc). And preheat your oven for 350 degrees.
You can buy either pre-crushed cracker crumbs, or you can crush them your self. About one package of graham crackers (a normal box has three packages) equals to 1 1/2 cups of crumbs.
Keep an eye on your assistant, and make sure he doesn't steal your ingredients. Tsk, tsk Mr. Assistant.
Add your 1/2 cup of sugar to the crumbs.
Now add your 5 tablespoons of melted butter. Now mix until everything is moist and crumbly.
Put about a tablespoon of the crumb mixture into the bottom of each paper lined cupcake mold. Now take a small glass (I used a shot glass) to gently press the crumbs down to form your crust. Now put these into the oven for about 5 minutes. Then remove and let cool.
Now, take all the ingredients for your cake and mix together. You will find the ingredients for this on the back of your cake mix box.
Once your crumb crust is cool, cut your large marshmallows in half. Place one half of each marshmallow on top of the crust and then fill each cup with some of the cake batter, a little less than half full.
Now pop them into the oven for about 20-25 minutes. Still at the 350 degrees
About 4-5 minutes before they are ready to come out. Stick the other half of the marshmallows on the tops of the cupcakes and finish baking. Let cool them enjoy.
(When you go to pull the cupcakes out of the oven to put the topping on before they are finished baking, you will see the marshmallow from the bottom puffing up through the batter.)