Preheat oven to 350 degrees and line a muffin tin with cupcake liners.
In a bowl, combine graham cracker crumbs, sugar and coconut oil until a crumb has formed. Press the mixture into the bottom of each muffin tin to form a thin crust. Bake for 5 minutes. Remove from the oven and let cool
Prepare brownie batter according to package directions. Stir in chocolate chips. Divid batter evenly between cupcake liners and bake for 20 - 22 minutes. Remove from oven and let cool.
Gently press down on brownie cupcakes. Top with mini marshmallows and bake for 2 - 3 minutes. Remove from oven and let cool.
