Prepare a sheet pan with parchment and set aside.
In a medium-sized bowl, combine the flour, baking soda, and salt. Set aside.
In a large bowl with a hand mixer or in a bowl of a stand mixer with a paddle attachment, cream the butter until smooth, about 1 minute. Add in the sugar and mix until light and fluffy, about 2-3 minutes. Once the butter and sugar are combined, add the eggs and vanilla.
Gradually add the flour mixture to the egg mixture on low speed. Once the flour mixture is added in, add in the hot chocolate packets. Mix until fully combined on low speed.
Scoop the batter into cookie dough balls, about 1 tablespoon each. Space them out evenly on the parchment paper and then cover with plastic wrap and chill the dough for at least one hour. Chill the dough for at least 1 hour and up to 1 day. If not planning to bake right away, chill the dough for an hour and then freeze.
Once the dough has chilled, preheat the oven to 350. Bake the cookies for 8-12 minutes, or until the edges start to look firm.
Let the cookies cool completely before adding the marshmallow topping. Once the cookies are cool, add about one tablespoon of the fluff to the top of the cookie. Spread it out using a spoon or an offset spatula.
With the topping spread out, torch it to your liking and enjoy! These cookies are best enjoyed fresh. They will last 2-3 days but will likely turn into a sticky mess in an airtight container. The marshmallow topping will spread out over time.
