Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a mixing bowl, whisk together the flour, cocoa powder, and salt.
In another bowl, mix the melted butter and sugar until well combined. Add the eggs and vanilla extract, and mix until smooth.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full.
Sprinkle graham cracker crumbs, mini marshmallows, and chocolate chips on top of each cupcake.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Let the cupcakes cool in the tin for 10 minutes, then transfer to a wire rack to cool completely.