Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.

In a large mixing bowl, cream softened butter and sugar together until light and fluffy, about 2-3 minutes.

Add the eggs one at a time, mixing well after each addition until fully incorporated.

Whisk together flour, cocoa powder, and baking soda in a separate bowl. Gradually combine with wet ingredients.

Fold in mini marshmallows and chocolate chunks evenly throughout the dough.

Drop portions of dough onto prepared baking sheets, spacing them about 2 inches apart.

Bake for 10-12 minutes until edges are crisp and centers look slightly underdone. Cool on the baking sheet for 5 minutes before transferring to a wire rack.