Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together butter and sugar until light and fluffy, about 3–5 minutes.

Add eggs to the creamed mixture, one at a time, ensuring each is incorporated before adding the next.

Whisk together flour, cocoa powder, and a pinch of salt in a separate bowl. Gradually add to wet ingredients, mixing on low speed.

Gently fold in chocolate chips and mini marshmallows until evenly distributed.

Scoop dough onto prepared baking sheet, leaving 2 inches between each scoop. Bake for 10–12 minutes.

Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.