Add the graham cracker crumbs, powdered sugar, peanut butter, and melted butter to a medium mixing bowl and stir well with a spoon to combine.
When mixture is well combined, spread into the bottom of a greased 8x8 baking dish.
Add the chocolate chips to a microwave safe bowl and microwave in 30 second bursts, stirring each time, until the chocolate has melted.
Pour the chocolate over the peanut butter mixture and smooth evenly over the top.
Sprinkle the m&m's over the melted chocolate.
Refrigerate for 2 hours before cutting and serving.
Video
Notes
Store in the refrigerator.To make life easier, add the m&ms to a plastic bag and crush them with a kitchen mallet rather than chopping them with a knife.