Preheat the oven to 350°F (175°C).
In a medium bowl, whisk together the gluten-free flour, cocoa powder, baking soda, and salt. Set aside.
In a large mixing bowl, cream together the butter, brown sugar, and granulated sugar until light and fluffy, about 2-3 minutes.
Beat in the eggs one at a time, then add the vanilla extract. Mix well.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in the chocolate chips and mini marshmallows until evenly distributed.
Drop rounded tablespoons of dough onto a baking sheet, spaced about 2 inches apart.
Bake for 10-12 minutes, until the edges are set but the centers remain soft.
Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.