Preheat the oven to 350 degrees Fahrenheit and line a sheet pan with parchment paper.
Use a mixer to beat the salted butter, granulated white sugar, and sour cream together until light and fluffy, about 3-5 minutes.
Beat in the eggs and then set the mixture aside.
In a large bowl, whisk the all-purpose flour, unsweetened cocoa powder, hot chocolate mix, and baking soda together.
Add the dry ingredient mixture into the wet ingredients and stir until just combined.
Fold in mini marshmallows and all of the semi-sweet chocolate chips.
Use a 2 Tablespoon cookie scoop to scoop the cookie dough into balls and drop them on the prepared sheet pan 2-inches apart from each other. Make sure there aren’t any marshmallows exposed on the cookie.
Bake the cookies in the oven for 10-12 minutes or until the edges have set.
Let cool for 10 minutes before plating and serving.