Preheat your oven to 350°F (175°C). Cream together butter, granulated sugar, and brown sugar until light and fluffy. Add eggs and vanilla extract, mixing until smooth.

In a separate bowl, whisk together flour, cocoa powder, baking soda, and salt. Gradually mix the dry ingredients into the butter mixture. Fold in chocolate chips.

Using a cookie scoop, drop the dough onto a lined baking sheet, spacing them 2 inches apart.

Bake for 12 minutes, allow the cookies to cool on the baking sheet for 3-5 minutes, then transfer them to a wire rack.

Microwave the mini marshmallows for 45 seconds until melted, stirring until smooth.

Pinch off small amounts of melted marshmallows and stretch them over each cookie to create a spider web design.