In a medium sized bowl add the cake mix, eggs, water and oil. Mix until blended, don't over mix, some lumps are fine.
Spray the slow cooker with non stick spray. Pour in the cake batter.
Sprinkle over the chocolate chips over the batter.
Cook on HIGH for 2 hours and 15 minutes.
When the cooking time is up, let the cake cool for 1-2 hours. (take lid off).
When the cake is cool, spread over the marshmallow creme, if needed microwave the marshmallow creme slightly so it's spreadable.
Crumble over the graham crackers and add the hershey pieces, and mini marshmallows.
Serve by scooping out the cake with a large spoon. Enjoy!
Video
Notes
Make sure it cools to room temperature before transferring it to an airtight container. It can be kept on the counter for up to a week (although it may not last that long).
A tub of vanilla buttercream frosting can be used instead of marshmallow creme.