Preheat oven to 350 degrees F. Line rimmed baking sheets with a Silpat and set aside.
Combine butter, sugar, brown sugar, and Adams pure vanilla extract in a bowl.
Add eggs, one at a time, mixing well after each addition.
Combine flour, baking soda, hot cocoa, and salt in a bowl and stir well.
Slowly add dry mix into butter mixture until blended well. Be careful not to over mix. Add chocolate chunks and mix briefly until they are distributed.
Fold mini marshmallows into cookie mix.
Using a medium cookie scoop, drop onto prepared cookie sheet, 2-inches apart. Bake for 14-16 minutes.
Remove from cookie sheet and let cool.
Notes
Some marshmallows may melt into the batter, that's OK. They will still taste delicious. If you'd like, press one or two mini marshmallows on top of each cookie before baking.