Pour Chex mix into a large mixing bowl and set aside
In a separate bowl, add chocolate chips, butter, and peanut butter. Heat in the microwave in 30 second increments, stirring between each cycle until mixture is melted and smooth. Add vanilla extract to melted chocolate sauce and stir until combined
Pour melted chocolate over cereal and mix thoroughly until cereal is coated with the chocolate
Add powdered sugar to gallon sized bag. Add cereal to bag and shake until all the cereal is covered with sugar
Place cereal on baking sheet lined with parchment paper or silicone mat and allow to cool
When cereal is cool, place in a bowl or container and mix in your desired candy or pretzels