In the bowl of a stand mixer with a paddle attachment, cream together the butter and sugar on medium-high speed. You want to mix them long enough that they become light and fluffy, but not so long that it starts to reform into lumps.

Add in the eggs to the creamed butter and sugar. Mix until these wet ingredients are smooth.

While your eggs are getting incorporated, whisk together flour, cocoa powder, baking soda, baking powder, and salt in a separate large bowl.

Slowly add the flour mixture to the butter mixture. Don't dump it in all at once, or you're guaranteed to have lumps in your cookie dough.

Use a cookie scoop to drop evenly-sized cookie dough balls on the prepared cookie sheet.

It's time to add some hot cocoa ingredients! Gently press your thumb into the center of each cookie to create a well. This is easiest if you dip your thumb in water first, or give it a quick spritz with nonstick cooking spray.

In each well, place a few mini marshmallows. This will melt into gooey marshmallow perfection!

Bake the cookie for 8 to 10 minutes. Move the cookies to a cooling rack, and then quickly top them with extra marshmallows and chocolate chips while they are still warm. Now it's time to enjoy!