Place waxed paper on a baking sheet. Set aside.
Using a large bowl, add cereal, set aside.
In a microwave safe bowl, microwave chocolate chips, peanut butter, and butter together for 30 second intervals, stirring between intervals, until smooth.
Once smooth, add vanilla. Stir and pour over cereal. Stir to combine.
Sprinkle powdered sugar over the Chex mixture, stir to coat.
Pour Chex mixture onto the prepared baking sheet.
Let cool completely before adding chocolate candies, mini marshmallows, and pretzels.
Store in airtight containers and place in the fridge.