Add butter to a medium saucepan and heat over medium heat. Cook butter stirring continuously until it turns golden brown and smells nutty. This takes about 5-7 minutes.
Pour the butter into a large bowl along with the chocolate chips. Stir until melted. Allow the chocolate to cool for 5 minutes.
Stir in the brown sugar, vanilla and eggs, one at a time until combined.
Fold in flour, cocoa, baking powder and salt. Mix until combined.Refrigerate the dough for an hour.
When you are ready to bake preheat the oven to 350 degrees. Line baking sheets with parchment paper or a non stick cooking mat.
Roll out tablespoon size cookies and flatten slightly with the palm of your hand.
Bake for 8 minutes or until set. Remove from the oven and add half of a marshmallow cut side down to each cookie.
Place back in the oven and bake for 2-3 additional minutes.
Allow the cookies to cool for 5 minutes on the baking sheet then transfer to a cooling rack to cool completely.
Once the cookies have completely cooled drizzle with chocolate frosting and enjoy!
Chocolate Frosting, optional
Add the butter, milk and cocoa powder to a small saucepan. Bring to a boil and cook for 1 minute.
Remove from the heat and allow the mixture to cool for 5 minutes.
Pour the mixture into a large bowl along with the powdered sugar. Whisk until creamy and clump free.
Immediately spoon glaze over cooled cookies. The longer frosting sits out the harder it becomes.