Prepare your 9x13 inch pan by oiling it down as well as the spoons or spatula you will be using.
In a large bowl add the butter and spread it around the bowl making sure to grease it.
Add the marshmallows and microwave for 2 minutes on high. Mix until smooth.
Add the dark chocolate and mix until the dark chocolate is melted and feel free to microwave to help melt the chocolate
Gradually add the cereal until it's barely sticking together. Pour into pan and spread evenly using the oiled spatula or spoon. Cool completely and serve.
Notes
*if you can't find any 11oz bags anything close to it works.