Combine melted butter and cocoa powder in a large bowl

Stir sugars into mixture

Add eggs and vanilla and mix until well combined

Stir in flour, and baking soda until a sticky dough forms

Chill dough for at least 1 hour

Once dough is chilled, preheat oven to 350 degrees

Use a 2 inch cookie scoop and roll dough into balls, place on baking sheet 2 inches apart

Bake for 10 minutes

Cut marshmallows in half. Once cookies come out of oven, place a cut marshmallow on top of warm cookie. Bake for another 2 minutes

When cookies come out oven, press marshmallow down, slightly

Cool cookies

While cookies are cooling, melt chocolate chips

Drizzle melted chocolate on cooled cookies