Preheat oven to 350°F and line a baking sheet with parchment paper.
Place butter in the bowl of a stand mixer and mix on high until light and fluffy.
Add in the sugar and mix until full combined. You may need to scrap down the sides and bottom of the bowl.
Add in the vanilla, eggs, and espresso powder, if using, and mix until combined. Mixture will look really wet.
Turn the mixture to low and add in the flour ½ cup at a time then add the cocoa powder.
Turn the mixer up to medium speed and add in the baking powder and salt. Make sure to scrape the sides and bottoms.
Mix in the chocolate chips.
In a small bowl combine the sugar and cocoa powder for the sugar topping. Roll each cookie dough ball in the toping then place on prepared baking sheet.
Bake for 9-10 minutes- until the cookies look just done and remove from oven. Turn oven to broil on High.
Once you’ve removed the cookies from the oven place a piece of chocolate and half a marshmallow on top of each cookie.
Place baking sheet back in oven for 1 minute or less! Watch them carefully- you want the tops of the marshmallows to brown slightly then they are done!
Remove from oven and enjoy!
Notes
Lisa's Tips and Tricks
* I used 1 cup semi-sweet regular and 1 cup semi-sweet large chocolate chips, but use whatever you have! *I like to cube my butter so it’s easier/faster for the mixer to whip up.