In a large sauce pan, on medium heat, melt the butter. Once melted add in the marshmallows and mix until they are just melted. Remove from heat.
Immediately add in the rice krispies to the melted marshmallow butter mixture. With a large wooden spoon mix until a sticky mixture is formed.
Add in the Ghouls mix M&M's and gently mix them in.
Scrape the mixture into a greased 9X13 baking pan. Gently press down with parchment paper to help spread the mixture across the whole pan and even out the top. Let cool, cut, and serve!
Notes
Make sure to press gently and mix gently once you begin working with the M&M's. This will help them from breaking and making a chocolate mess.
Once completely cooled make sure to cover with a lid, plastic wrap, or tin foil to maintain freshness.
Add in a ½ cup of candy corn if desired!
When cooling, top with halloween themed sprinkles for more spooky fun.