Pour the sugar for rolling into a small bowl and set aside.Preheat the oven to 350 F (177 C) for about 20-30 minutes before baking the cookies. Line a large baking sheet with parchment paper. Allow the dough to rest while the oven preheats for 30 minutes or transfer to the fridge to store for longer.
Using a large cookie scoop (3 tablespoons, 45 ml), scoop the chocolate sugar cookie dough into the palm of a clean hand. Gently press the dough into a disk. Insert 6 - 7 mini marshmallows or one regular sized marshmallow into the center. Gently lift the sides up and around the marshmallows.