Place butter, brown sugar, and granulated sugar into a large bowl, then whisk until smooth.
Whisk in eggs and vanilla until combined.
Fold in flour, cocoa powder, hot chocolate, salt, baking powder, and baking soda until incorporated, then stir in the chocolate chips.
Line 4 baking sheets with silicone baking mats.
Use a large cookie scoop to scoop out 32 dough balls — place 8 onto each prepared baking sheet.
Optional - chill in the fridge for 30 minutes. This helps the cookies from spreading.
Preheat oven to 350 degrees F, then baked the dough balls for 12-15 minutes.
Remove cookies from oven and turn the oven to broil.
Top each cookie with 1 dove chocolate and 1 marshmallow (you may need to press down gently, but firmly to get the marshmallow to stay on the cookie).
Broil on the middle rack until the marshmallow is golden brown, about 30-60 seconds (time varies depending on how hot your broiler is).
Remove from oven, then use your fingers to gently squish the toasted marshmallow to flatten slightly and enjoy warm!
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