01 -
In a medium bowl, stir together the cocoa powder, salt, flour, and baking soda.
02 -
Use an electric mixer to whip up the butter with sugar until it’s soft and fluffy. This'll take around 3–4 minutes.
03 -
Add the eggs one at a time, mixing after each, then pour in the vanilla.
04 -
Work the dry mix into the wet mixture in small parts until just mixed. Chill the dough for an hour.
05 -
Form small balls, press an indent in each, add marshmallow cream, and swirl. Pop them in the oven at 350°F for 10–12 minutes.