Preheat the oven to 350 F. In a medium bowl, whisk together flour, cocoa powder, salt, and baking soda. In a large bowl, combine butter with sugar until fluffy. Add in egg and vanilla extract and mix until smooth.
Add in the flour mixture, and mix until it is fully combined. Fold in the crushed graham crackers, chocolate chips, and mini marshmallow bits.
Roll the cookie dough into balls, and place them onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes. Remove from the oven and top each cookie with one chocolate kiss.
