In a medium microwave safe bowl, melt the chocolate chips, peanut butter, and butter for 1 minute. Stir, and microwave again in 30 second increments until fully melted.
Stir in the vanilla extract.
In a large bowl, add in the chex cereal.
Pour the melted chocolate mixture over the chex, carefully tossing until the cereal is covered.
Add the chocolate covered cereal to a large freezer sized ziplock bag with the powdered sugar. Shake until the chocolate chex is fully covered with powdered sugar.
Transfer to a clean serving bowl and add in the candy corn, m&ms, and sprinkles carefully tossing. Serve!