1) In a mixing bowl, cream together butter and sugars until fluffy. Add eggs and vanilla and mix until well incorporated.
2) In a separate bowl, stir together flour, hot chocolate mix, salt and baking soda.
3) Slow add the flour mixture to the sugar mixture. Mix until well blended.
4) Place by rounded teaspoon onto parchment lined baking sheets.
5) Bake at 350 for 10 minutes or until slightly firm.
6) As soon as you remove the cookies from the oven, begin topping with marshmallows.
7) After cooling for a few minutes on the baking sheet, move to wire wrack until completely cool.Recipe by DineAndDish.com