Microwave chocolate chips for 30 seconds, stir. Continue to microwave for 10-15 second intervals, stirring after each interval, until chocolate is melted and smooth. Set bowl aside and allow to cool to room temperature.
In a large bowl, beat butter and both sugars until light and fluffy.
Add melted chocolate. Stir.
Add eggs one at a time, beating after each addition.
Mix flour, cocoa, baking soda and salt in a separate bowl. Add to wet ingredients. Mix until incorporated. Fold in chocolate chunks, mint bits, and marshmallows.
Fill pint containers with cookie dough and refrigerate up to 4 days or freeze for a month. Allow dough to rise to room temperature before baking.
Preheat oven to 350 degrees. Line baking sheets with parchment paper. Drop dough in tablespoon size balls about an inch apart. If dough has been frozen you might want to flatten dough slightly using the bottom of a glass or the back of a spatula. Bake for 10-12 minutes, edges will be lightly cracked but centers will be soft.
Cool slightly on baking sheet then transfer to a wire rack to finish cooling.