• Cream butter and sugar together.
• Add in the milk, egg, and vanilla. Mix until well combined.
• Combine the flour, cocoa, salt, and baking soda.Gradually add to the creamed mixture. Beat until well combined.
• Drop by rounded teaspoonfuls onto parchment-lined baking sheets.
• Bake at 350 for 8 minutes.
• While the cookies are baking, cut the marshmallows in half.
• Press a marshmallow half onto each cookie (cut side down).
• Return the cookies to the oven for an additional 2 minutes and then let the cookies cool completely on a rack.

Icing

• To make the icing, combine milk, cocoa, and butter in a small saucepan and bring to a boil.
• Boil for one minute stirring continuously.
• Let the icing cool slightly and then transfer to a small bowl.
• Add the confectioners' sugar and vanilla and beat until smooth.
• Spoon icing into a plastic bag. Cut the corner (do this over the bowl) and ice the cookies.
• Let the icing harden and enjoy!