Preheat oven to 350-degrees farenheit
Melt the ½-cup of dark chocolate and the ½-cup of white chocolate gently in a stainless steel bowl over boiling water in a pot on the stovetop.
Beat the butter and sugar together until thick and creamy. Add in the eggs. Add the cooled melted chocolate and vanilla extract. Mix until the ingredients are well mixed.
Sift the flour, Cacao powder, baking soda, and salt together into a bowl and sift together.
Fold the dry ingredients into the wet ingredients. Add the 1-cup dark chocolate chips and the 1-cup white chocolate chips and mix until combined. Do not overmix the batter.
Let the dough sit in the fridge to chill for 5-minutes, but don't let the dough sit too long. We are using melted chocolate so if the dough sits for too long it will harden.
Scoop the cookie dough with a cookie dough scooper into 1-inch balls on a lined cookie sheet.
Bake at 350-degrees farenheit for 8-minutes. The cookies should resemble brownies and should be cake-like in the middle.
Once baked, top with a few small marshmallows and pop the cookies back into the oven for 3-minutes.
Remove the cookies from the oven and let cool for 5-minutes on the baking sheet then carefully, using a spatula, transfer the cookies to cooling racks.
Let the cookies cool for 15-minutes and enjoy!