In a medium bowl, whisk together flour, cocoa powder, baking soda, salt, and cinnamon. Set aside.
In a large bowl or stand mixer, cream together butter, brown sugar, and granulated sugar until light and fluffy, about 3-4 minutes.
Beat in eggs one at a time, then stir in vanilla extract.
Gradually mix in the dry ingredients until just combined.
Fold in chocolate chips and 1 cup of mini marshmallows.
Cover the dough and refrigerate for at least 30 minutes.
Preheat oven to 350°F. Line baking sheets with parchment paper.
Scoop rounded tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake for 8 minutes, then remove from oven and quickly press a few extra mini marshmallows on top of each cookie.
Return to oven and bake for an additional 2-4 minutes, until edges are set but centers are still soft.
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
Notes
Note: The marshmallows may ooze out during baking, creating a gooey texture. If you prefer a neater cookie, make sure no marshmallows are on the outside of the dough ball before baking.
Pro Tip:
For the best results, don’t skip the chilling step! Chilling the dough for at least 30 minutes helps the cookies keep their shape and gives them that perfect texture. Plus, rolling the dough into balls can help make every cookie look extra neat!