In a large bowl, beat the butter, white sugar, and brown sugar with a handheld electric mixer until creamy. Beat in the eggs and vanilla.
Add the hot cocoa mix, flour, cocoa powder, salt, soda, and baking powder. Stir just until barely combined. Fold in the mini chocolate chips and mallow bits.
Cover the dough and chill for 30 minutes.
Preheat your oven to 350 degrees. Line a cookie sheet with silicone liner or parchment paper, or spray with cooking spray.
Roll dough into tablespoon-sized balls. (I like to use a cookie scoop to portion the cookies.) Place at least 2 inches apart on the prepared baking sheet.
Bake cookies at 350° for 9-11 minutes, or until barely set in the middle.
Immediately press a few of the milk chocolate chips on the top of each cookie. (I also like to press some extra mallow bits on the cookies.)
Let cool on the pan for 4-5 minutes, then remove to wire racks to cool completely.
Notes
-You can chill the dough for 24 hours. Let it sit at room temperature for 45-60 minutes or until it is soft enough to scoop.