Making your Homemade Chocolate Marshmallow Swirl Cookies is easy if you follow these simple steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.

2. Mix Dry Ingredients: In a medium bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt. Set aside.

3. Cream Butter and Sugars: In a large bowl, use an electric mixer to cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

4. Add Egg and Vanilla: Beat in the egg and vanilla extract until well combined.

5. Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.

6. Incorporate Marshmallows: Gently fold in the mini marshmallows and chocolate chips (if using).

7. Form Cookies: Drop spoonfuls of cookie dough onto the prepared baking sheet, leaving space between each dollop as they will spread while baking.

8. Bake: Place the baking sheet in the preheated oven and bake for 10-12 minutes, or until the edges are firm but the centers are still soft.

9. Cool: Remove from the oven and let the cookies cool on the baking sheet for about 10 minutes before transferring them to a wire rack to cool completely.

These delicious cookies are now ready to be devoured!