Prepare the Dough

1. Preheat Oven: Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
2. Cream Butter and Sugars: In a large mixing bowl, cream the butter, granulated sugar, and brown sugar until light and fluffy.
3. Add Eggs and Vanilla: Beat in the eggs one at a time, followed by the vanilla extract. Mix until fully incorporated.
4. Combine Dry Ingredients: In a separate bowl, whisk together the flour, cocoa powder, baking soda, and salt.
5. Mix Wet and Dry: Gradually add the dry ingredients to the wet mixture, mixing until just combined.
6. Stir in Chocolate Chips: Fold in the chocolate chips for bursts of chocolatey goodness.

Shape and Bake

1. Form Cookies: Using a cookie scoop or tablespoon, drop rounded spoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
2. Bake: Bake for 10 minutes, then quickly remove from the oven.

Add Marshmallow Topping

1. Top with Marshmallows: Place 2-3 mini marshmallows on top of each partially baked cookie.
2. Finish Baking: Return cookies to the oven and bake for an additional 2-3 minutes, or until the marshmallows are slightly melted and golden.

Cool and Serve

1. Cool: Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
2. Optional Garnishes: Dust with powdered sugar, sprinkle crushed candy canes, or drizzle melted chocolate for added flair.