01 - 
                Grab a medium bowl. Toss in the flour, cocoa powder, salt, and baking soda. Give it a good sweep with your whisk until you don't see any streaks.
              
              
              
                02 - 
                In a big bowl, use your mixer to fluff up the softened butter and the sugar. Let it whip for about 3–4 minutes so it's super light and airy.
              
              
              
                03 - 
                Drop eggs in one by one, making sure each is mixed in before adding the next. Pour in the vanilla last, then stir it all until you get a creamy look.
              
              
              
                04 - 
                Slowly add the dry bowl into your wet bowl using your mixer on the lowest speed. Keep mixing until it's just barely sticking together and looks like dough.
              
              
              
                05 - 
                Cover the finished dough and let it hang out in the fridge for at least 1 hour. Makes scooping it much easier and keeps your cookies from spreading too much.
              
              
              
                06 - 
                Fire up your oven to 350°F (175°C) about 20 minutes before you’ll bake. Grab two baking sheets and lay out some parchment or a silicone mat.
              
              
              
                07 - 
                Scoop balls of cold dough with your cookie scoop or spoon. Set them out on the sheets with a couple inches between each. Make a dip in the center, drop in some marshmallow cream, and swirl a bit with a toothpick.
              
              
              
                08 - 
                Slide cookies into the oven for 10–12 minutes. You want the edges set but middles still a little soft. If you want extra goo, drop on a bit more marshmallow halfway through.
              
              
              
                09 - 
                Leave the cookies on the tray for 5 minutes to set up, then move them to a wire rack so they can finish cooling and the middle gets just right.